THE FIRST DAY
SALVIATI, SAGREDO, AND SIIMPLICIO
SALVIATI. Yesterday we resolved to meet today and discuss as clearly and in as
much detail as possible the character and the efficacy of those laws of nature
which up to the present have been put forth by the partisans of the Aristotelian
and Ptolemaic position on the one hand, and by the followers of the Copemican
system on the other. Since Copernicus places the earth among the movable heavenly
bodies, making it a globe like a planet, we may well begin our discussion by
examining the Peripatetic steps in arguing the impossibility of that hypothesis;
what they are, and how great is their force and effect. For this it is necessary
to introduce into nature two substances which differ essentially. These are the
celestial and the elemental, the former being invariant and eternalo the latter,
temporary and destructible. This argument Aristotle treats in his book De Caelo,
introducing it with some discourses dependent upon certain general assumptions,
and afterwards confirming it by experiments and specific demonstrations.
Following the same method, I shall first propound, and then freely speak my
opinion, submitting myself to your criticisms -- particularly those of Simplicio,
that stout champion and defender of Aristotelian doctrines.
The first step in the Peripatetic arguments is Aristotle's proof of the
completeness and perfection of the world. For, he tells us, it is not a mere
line, nor a bare surface, but a body having length, breadth, and depth. Since
there are only these three dimensions, the world, having these, has them all,
and, having the Whole, is perfect. To be sure, I much wish that Aristotle had
proved to me by rigorous deductions that simple length constitutes the dimension
which we call a line, which by the addition of breadth becomes a surface; that by
further adding altitude or depth to this there results a body, and that after
these three dimensions there is no passing farther‹so that by these three alone,
completeness, or, so to speak, wholeness is concluded. Especially since he might
have done so very plainly and speedily.
SIMP. What about the elegant demonstrations in the second, third, and fourth
texts, after the definition of "continuous"? Is it not there first proved that
there are no more than three dimensions, since Three is everything, and
everywhere? And is this not confirmed by the doctrine and authority of the
Pythagoreans, who say that all things are determined by three -- beginning, middle,
and end -- which is the number of the Whole? Also, why leave out another of his
reasons; namely, that this number is used, as if by a law of nature, in
sacrifices to the gods? Furthermore, is it not dictated by nature that we
attribute the title of "all" to those things that are three, and not less? For
two are called "both," and one does not say "all" unless there are three.
You have all this doctrine in the second text. Afterwards, in the third we read,
ad pleniorem Scientiam, that All, and Whole, and Perfect are formally one and the
same; and that therefore among figures only the solid is complete. For it alone
is determined by three, which is All; and, being divisible in three ways, it is
divisible in every possible way. Of the other figures, one is divisible in one way,
and the other in two, because they have their divisibility and their continuity
according to the number of dimensions allotted to them. Thus one figure is
continuous in one way, the other in two; but the third, namely the solid,
is so in every way.
Moreover, in the fourth text, after some other doctrines, does he not clinch the
matter with another proof? To wit: a transition is made only according to some
defect; thus there is a transition in passing from the line to the surface,
because the line is lacking in breadth. But it is impossible for the perfect to
lack anything, being complete in every way; therefore there is no transition
beyond the solid or body to any other figure.
Do you not think that in all these places he has sufficiently proved that there
is no passing beyond the three dimensions, length, breadth, and thickness; and
that therefore the body, or solid, which has them all, is perfect?
SALV. To tell you the truth, I do not feel impelled by all these reasons to grant
any more than this: that whatever has a beginning, middle, and end may and ought
to be called perfect. I feel no compulsion to grant that the number three is a
perfect number, nor that it has a faculty of conferring perfection upon its
possessors. I do not even understand, let alone believe, that with respect to
legs, for example, the number three is more perfect than four or two; neither do
I conceive the number four to be any imperfection in the elements, nor that they
would be more perfect if they were three. Therefore it would have been better for
him to leave these subtleties to the rhetoricians, and to prove his point by
rigorous demonstrations such as are suitable to make in the demonstrative
SIMP. It seems that you ridicule these reasons, and yet all of them are doctrines
to the Pythagoreans, who attribute so much to numbers. You, who are a
mathematician, and who believe many Pythagorean philosophical opinions, now seem
to scorn their mysteries.
SALV. That the Pythagoreans held the science of the human understanding and
believed it to partake of divinity simply because it understood the nature of
numbers, I know very well; nor am I far from being of the same opinion. But that
these mysteries which caused Pythagoras and his sect to have such veneration for
the science of numbers are the follies that abound in the sayings and Writings of
the vulgar, I do not believe at all. Rather I know that, in order to prevent the
things they admired from being exposed to the slander and scorn of the common
people, the Pythagoreans condemned as sacrilegious the publication of the most
hidden properties of numbers or of the incommensurable and irrational quantities
which they investigated. They taught that anyone who had revealed them was
tormented in the other world. Therefore I believe that some one of them, just to
satisfy the common sort and free himself from their inquisitiveness, gave it out
that the mysteries of numbers were those trifles which later spread among the
vulgar. Such astuteness and prudence remind one of the wise young man who, in
order to stop the importunity of his mother or his inquisitive wife -- I forget
which -- who pressed him to impart the secrets of the Senate, made up some story
which afterwards caused her and many other women to be the laughing-stock of that
SIMP. I do not want to join the number of those who are too curious
about the Pythagorean mysteries. But as to the point in hand, I reply that the
reasons produced by Aristotle to prove that there are not and cannot be more than
three dimensions seem to me conclusive; and I believe that if a more cogent
demonstration had existed, Aristotle would not have omitted it.
SAGR. You might at least add, "if he had known it or if it had occurred to him."
Salviati, you would be doing me a great favor by giving me some effective
arguments. if there are any clear enough to be comprehended by me.
SALV. Not only by you, but by Simplicio too; and not merely comprehended,
but already known -- though perhaps without your realizing it. And to make
them easier to understand, let us take this paper and pen which I see already
prepared for such occasions, and draw a few figures.
First we shall mark these two points, A and B, and draw from one to the other the
curved lines ACB and ADE, and the straight line P3. (Fig. 1) I ask which of them
is to your mind the one that determines the distance between the ends A and B,
SAGR. I should say the straight line, and not the curves, because the
straight one is shorter and because it is unique, distinct, and determinate; the
infinite others are indefinite, unequal, and longer. It seems to me that the
choice ought to depend upon that which is unique and definite.
SALV. We have the
straight line, then, as determining the distance between the two points.
We now add another straight line parallel to AB -- let it be CD -- so that
between them there lies a surface of which I want you to show the breadth. (Fig.
2) Therefore starting from point A, tell me how and which way you will go,
stopping on the line CD, so as to show me the breadth included between those
lines. Would you determine it according to the measure of the curve AF, or the
straight line AF, or. . . ?
SIMP. According to the straight line AF, and not
according to the curve, such being already excluded for such a use.
SAGR. But I should take neither of them, seeing that the straight line AF
runs obliquely. I should draw a line perpendicular to CD, for this would seem to
me to be the shortest, as well as being unique among the infinite number of
longer and unequal ones which may be drawn from the point A to every other point
of the opposite line CD.
SALV. Your choice and the reason you adduce for it seem
to me most excellent. So now we have it that the first dimension is determined by
a straight line; the second (namely, breadth) by another straight line, and not
only straight, but at right angles to that which determines the length. Thus we
have defined the two dimensions of a surface; that is, length and breadth.
But suppose you had to determine a height -- for example, how high this
platform is from the pavement down below there. Seeing that from any point in the
platform we may draw infinite lines, curved or straight, and all of different
lengths, to the infinite points of the pavement below, which of all these lines
would you make use of?
SAGR. I would fasten a string to the platform and, by hanging a plummet
from it, would let it freely stretch till it reached very near to the pavement;
the length of such a string being the straightest and shortest of all the lines
that could possibly be drawn from the same point to the pavement, I should say
that it was the true height inthis case.
SALV. Very good. And if, from the point on the pavement indicated by this
hanging string (taking the pavement to be level and not inclined), you should
produce two other straight lines, one for the length and the other for the
breadth of the surface of the pavement, what angles would they make with the
SAGR. They would surely meet at right angles, since the string faIls
perpendicularly and the pavement is quite flat and level.
SALV Therefore if you assign any point for the point of origin of your
measurements, and from that produce a straight line as the determinant of the
first measurement (that is, of the length) it will necessarily follow that the
one which is to define the breadth leaves the first at a right angle. That which
is to denote the altitude, which is the third dimen sion, going out from the same
point, also forms right angles and not oblique angles with the other two. And
thus by three perpendiculars you will have determined the three dimensions AB
length, AC breadth, and AD height, by three unique, definite, and shortest lines.
And since clearly no more lines can meet in the said point to make right
angles with them, and the dimensions must be determined by the only straight
lines which make right angles with each other, then the dimensions are no more
than three; and whatever has the three has all of them, and that which has all of
them is divisible in every way, and that which is so, is perfect, etc.
SIMP. Who says that I cannot draw other lines? Why may I not bring another line from
beneath to the point A, which will be perpendicular to the rest?
SALV. Surely you cannot make more than three straight lines meet in the same
point and form right angles with each other!
SAGR. Yes, because it seems to me that what Simphcio means would be the same DA
prolonged downward. In that way there might also be drawn two others; but they
would be the same as the first three, differing only in that whereas now they
merely touch, they would then intersect. But this would not produce any new
SIMP. I shall not say that this argument of yours cannot be conclusive. But I
still say, with Aristotle, that in physical (naturali) matters one need not always require a mathematical demonstration.
SAGR. Granted, where none is to be had; but when there is one at hand, why
do you not wish to use it? But it would be good to spend no more words on this
point, for I think that Salviati will have conceded both to Aristotle and to you,
without further demonstration, that the world is a body, and perfect; yea, most
perfect, being the chief work of God.
SALV. Exactly so. Therefore leaving the general
contemplation of the whole, let us get to the consideration of the pans.
Aristotle in his first division separates the whole into two differing and, in a
way, contrary parts: namely, the celestial and the elemental, the former being
ingenerable, incorruptible, inalterable, impenetra ble, etc.; the latter being
exposed to continual alteration, mutation, etc. He takes this difference from the
diversity of local motions as his original principle. With this step he
Leaving, so to speak, the sensible world and retiring into the ideal world, he
begins architec tonically to consider that, nature being the principle of motion,
it is appropriate that natural bodies should be endowed with local motion. He
then declares local motions to be of three kinds: namely, circular, straight, and
mixed straight-and-circular. The first two he calls simple, because
of all lines only the circular and the straight are simple. Hereupon, restricting
himself somewhat, he newly defines among the simple motions one, the circular, to
be that which is made around the center; and the other, the straight, to be
upward and downward -- upward, that which goes from the center; and downward,
whatever goes toward the center. And from this he infers it to be necessary and
proper that all simple motions are confined to these three kinds; namely, toward
the center, away from the center, and around the center. This answers, he says,
with a certain beautiful harmony to what has been said previously about the body;
it is perfect in three things, and its motion is likewise.
These motions being established, he goes on to say that some natural bodies being
simple, and others composites of those (and he calls those bodies simple which
have a natural principle of motion, such as fire and earth), it is proper that
simple motions should be those of simple bodies, and that mixed motions should
belong to compound bodies; in such a way, moreover, that compounds take the
motion of that part which predominates in their composition.
SAGR. Wait awhile, Salviati, for in this argument 1 find so many doubts
assailing me on all sides that I shall either have to tell them to you if I want
to pay attention to what you are going to say, or withhold my attention in order
to remember my doubts.
SALV. I shall willingly pause, for I run the same risk too, and am on the
verge of getting shipwrecked. At present I sail between rocks and boisterous
waves that are making me lose my bearings, as they say. Therefore, before I
multiply your difficulties, propound them.
[pp.16-50. The three now embark on a discussion motion and velocity -- which leads in time to arguments about the location to the center of the universe and whether or not the heavens are actually incorruptible -- with Simplicio continuing to generally adhere to and defend Aristotle 's theories, while Sagredo and Salviati, using a combination of logic and specific examples in nature, continue to cast doubt on the coherence of the Aristotelian model, pointing out inconsistencies and fallacies.]
SALV. I see we are once more going to engulf ourselves in a boundless sea
from which there is no getting out, ever. This is navigating without compass,
stars, oars, or rudder, in which we must needs either pass from bank to bank or
run aground, or sail forever lost. If, as you suggested, we are to get on with
our main subject, it is necessary for the present to put aside the general
question whether straight motion is necessary in
nature and is proper to some bodies, and proceed to demonstrations, observations,
and particular experiments. First we must propound all those that have been put
forward to prove the earth's stability by Aristotle, Ptolemy, and others, trying
next to resolve them. Finally we must produce those by which a person may become
persuaded that the earth, no less than the moon or any other planet, is to be
numbered among the natural bodies that move circularly.
SAGR. I submit to the latter more willingly, as I am better satisfied with
your architectonic and general discourse than with that of Aristotle. For yours
satisfies me without the least misgiving, while the other blocks me in some way
at every turn. Nor do I know why Simplicio should not be quickly satisfied with
the argument you put forward to prove that motion in a straight line can have no
place in nature, so long as we suppose the parts of the universe to be disposed
in the best arrangement and perfectly ordered.
SALV. Stop there, Sagredo. for now
a way occurs to me in which Simplicio may be given satisfaction, provided only
that he does not wish to stay so closely tied to every phrase of Aristotle's as
to hold it sacrilege to depart from a single one of them.
There is no doubt that to maintain the optimum placement and perfect order of the
parts of the universe as to local situation, nothing will do but circular motion
or rest. As to motion by a straight line, I do not see how it can be of use for
anything except to restore to their natural location such integral bodies as have
been accidentally removed and separated from their whole, as we have just
Let us now consider the whole terrestrial globe, and let us see what can happen
to make it and the other world bodies keep themselves in the natural and best
disposition. One must either say that it is at rest and remains perpetually
immovable in its place, or else that it stays always in its place but revolves
itself, or finally that it goes about a center, moving along the
circumference of a circle. Of these events, Aristotle and Ptolemy and all their
followers say that it is the first which has always been observed and which will
be forever maintained; that is, perpetual rest in the same place. Now why, then,
should they not have said from the start that its natural property is to remain
motionless, rather than making its natural motion downward, a motion with which
it never did and never will move? And as to motion by a straight line, let it be
granted to us that nature makes use of this to restore particles of earth, water,
air, fire, and every other integral mundane body to their whole, when any of them
find themselves separated and transported into some improper place unless this
restoration can also be made by finding some more appropriate circular motion. It
seems to me that this original position fits all the consequences much better,
even by Aristotle's own method, than to attribute straight motion as an intrinsic
and natural principle of the elements. This is obvious; for let me ask the
Peripatetic if, being of the opinion that celestial bodies are incorruptible and
eternal, he believes that the terrestrial globe is not so, but corruptible and
mortal, so that there will come a time when, the sun and moon and other stars
continuing their existence and their operations, the earth will not
be found in the universe but will be annihilated along with the rest of the
elements, and I am certain that he would answer, No. Therefore generation and
corruption belong to the parts and not to the whole; indeed, to very small and
superficial parts which are insensible in comparison to the whole mass. Now since
Aristotle argues generation and corruption from the contrariety of straight
motions, let us grant such motions to the parts, which alone change and decay.
But to the whole globe and sphere of the elements will be ascribed either
circular motion or perpetual continuance in its proper place -- the only
tendencies fined for the perpetuation and maintenance of perfect order.
What is thus said of earth may be said as reasonably of fire and of the greater
part of the air, to which elements the Peripatetics are forced to assign as an
intrinsic and natural motion one with which they were never moved and never will
be, and to abolish from nature that motion with which they move, have moved, and
are to be moved perpetually. I say this because they assign an upward motion to
air and fire, which is a motion that never belongs to the said elements, but only
to some of their parti cles -- and even then only to restore them to perfect
arrangement when they are out of their natural places. On the other hand, they
call circular motion (with which they are incessantly moved) preternatural to
them, forgetting what Aristotle has said many times, that nothing violent can
last very long.
SIMP. To all these things we have the most suitable answers, which I omit
for the present in order that we may come to the particular reasons and sensible
experiments which ought to be finally preferred, as Aristotle well says, above
anything that can be supplied by human argument.
SAGR. Then what has been said up to now will serve to place under
consideration which of two general arguments has the more probability. First
there is that of Aristotle, who would persuade us that sublunar bodies are by
nature generable and corruptible, etc., and are therefore very different in
essence from celestial bodies, these being invariant, ingenerable, incorruptible,
etc. This argument is deduced from differences of simple motions. Second is that
of Salviati, who assumes the integral parts of the world to be disposed in the
best order, and as a necessary consequence excludes straight motions for simple
natural bodies as being of no use in nature; he takes the earth to be another of
the celestial bodies, endowed with all the prerogatives that belong to them. The
latter reasoning suits me better up to this point than the other. Therefore let
Simplicio be good enough to produce all the specific arguments, experiments, and
physical and astronomical, by which one may be fully persuaded
that the earth differs from the celestial bodies, is immovable, and is located in
the center of the universe, or anything else that would exclude the earth from
being movable like a planet such as Jupiter, or the moon, etc. And you, Salviati,
have the kindness to reply step by step.
SIMP. For a beginning, then, here are two powerful demonstrations proving the
earth to be very different from celestial bodies. First, bodies that are
generable corruptible, alterable, etc., are quite different from those that are
ingenerable, incorruptible, inalterable, etc. The earth is generable,
corruptible, alterable, etc., while celestial bodies are ingenerable,
incorruptible, inalterable, etc. Therefore the earth is very different from the
SAGR. With your first argument, you bring back to the table what has been
standing there all day and has just now been carried away.
SIMIP. Softly, sir; hear the rest, and you will see how different it is from
that. Formerly the minor premise was proved a priori, and now I wish to prove it
a posteriori. See for yourself whether this is the same thing. I shall prove the
minor, because the major is obvious.
Sensible experience shows that on earth there are continual generations,
corruptions, alter-ations, etc., the like of which neither our senses nor the
traditions or memories of our ancestors have ever detected in heaven; hence
heaven is inalterable, etc., and the earth alterable, etc., and therefore
different from the heavens.
The second argument I take from a principal and essential property, which is
this: whatever body is naturally dark and devoid of light is different from
luminous and resplendent bodies; the earth is dark and without light, and
celestial bodies are splendid and full of light; therefore, etc. Answer these, so
that too great a pile does not accumulate, and then I will add others.
SALV. As to the first, for whose force you appeal to experience, I wish you would
tell me precisely what these alterations are that you see on the earth and not in
the heavens, and on account of which you call the earth alterable and the heavens
SIMP. On earth I continually see herbs, plants, animals generating and decaying;
winds, rains, tempests, storms arising; in a word, the appearance of the earth
undergoing perpetual change. None of these changes are to be discerned in
celestial bodies, whose positions and configurations correspond exactly with
everything men remember, without the generation of anything new there or the
corruption of anything old.
SALV. But if you have to content yourself with these visible, or rather these
seen experiences, you must consider China and America celestial bodies, since you
surely have never seen in them these alterations which you see in Italy.
Therefore, in your sense, they must be inalter-able.
SIMP. Even if I have never seen such alterations in those places with my own
senses, there are reliable accounts of them; besides which, cum eadem sit ratio
totius et partium those counties being a pan of the earth like ours, they must be alterable like this.
SALV. But why have you not observed this, instead of reducing yourself to having
to believe the tales of others? Why not see it with your own eyes?
SIMP. Because those countries are far from being exposed to view; they are so
distant that our sight could not discover such alterations in them.
SALV. Now see for yourself how you have inadvertently revealed the fallacy of
your argument. You say that alterations which may be seen near at hand on earth
cannot be seen in America because of the great distance. Well, so
much the less could they be seen in the moon, which is many hundreds of times
more distant. And if you believe in alterations in Mexico on the basis of news
from there, what reports do you have from the moon to convince you that there are
no alterations there? From your not seeing alterations in heaven (where if any
occurred you would not be able to see them by reason of the distance, and from
whence no news is to be had), you cannot deduce that there are none, in the same
way as from seeing and recognizing them on earth you correctly deduce that they
do exist here.
SIMIP. Among the changes that have taken place on earth I can find some so great
that if they had occurred on the moon they could yen well have been observed here
below. From the oldest records we have it that formerly, at the Straits of
Gibraltar, Abila and Calpe were joined together with some lesser mountains which
held the ocean in check; but these mountains being separated by some cause, the
opening admitted the sea, which flooded in so as to form the Mediterranean. When
we consider the immensity of this, and the difference in appearance which must
have been made in the water and land seen from afar, there is no doubt that such
a change could easily have been seen by anyone then on the moon. Just so would
the inhabitants of earth have discovered any such alteration in the moon; yet
there is no history of such a thing being seen. Hence there remains no basis for
saying that anything in the heavenly bodies is alterable, etc.
SALV. I do not make bold to say that such great changes have taken place in the
moon, but neither am I sure that they could not have happened. Such a mutation
could be represented to us only by some variation between the lighter and the
darker parts of the moon, and I doubt whether we have had observant
selenographers on earth who have for any considerable number of years provided us
with such exact selenography as would make us reasonably conclude that no such
change has come about in the face of the moon. Of the moon's appearance, I find
no more exact description than that some say it represents a human face; others,
that it is like the muzzle of a lion; still others, that it is Cain with a bundle
of thorns on his back. So to say "Heaven is inalterable, because neither in the
moon nor in other celestial bodies are such alterations seen as are discovered
upon the earth" has no power to prove anything.
SAGR. This first argument of Simplicio's leaves me with another haunting doubt
which I should like to have removed. Accordingly I ask him whether the earth was
generable and corruptible before the Mediterranean inundation, or whether it
began to be so then?
SIMP. It was without doubt generable and corruptible before, as well; but that
was so vast a mutation that it might have been observed as far as the moon.
SAGR. Well, now; if the earth was generable and corruptible before that flood,
why may not the moon be equally so without any such change? Why is something
necessary in the moon which means nothing on the earth?
SALV. A very penetrating remark. But I am afraid that Simplicio is altering the
meaning a bit in this text of Aristotle and the other Peripatetics. They say that
they hold the heavens to be inalterable because not one star there has ever been
seen to be generated or corrupted, such being probably a lesser part of heaven
than a city is of the earth; yet innumerable of the latter have been destroyed so
that not a trace of them remains.
SAGR. Really, I thought otherwise, believing that Simplicio distorted this
exposition of the text so that he might not burden the Master and his disciples
with a notion even more fantastic than the other. What folly it is to say, "The
heavens are inalterable because stars are not generated or corrupted in them." Is
there perhaps someone who has seen one terrestrial globe decay and another
regenerated in its place? Is it not accepted by all philosophers that very few
in the heavens are smaller than the earth, while a great many are much
bigger? So the decay of a star in heaven would be no less momentous than for the
whole terrestrial globe to be destroyed! Now if, in order to be able to introduce
generation and corruption into the universe with certainty, it is necessary that
as vast a body as a star must be corrupted and regenerated, then you had better
give up the whole matter; for I assure you that you will never see the
terrestrial globe or any other integral body in the universe so corrupted that,
after having been seen for many ages past, it dissolves without leaving a trace
SALV. But to give Simplicio more than satisfaction, and to reclaim him if
possible from his error, I declare that we do have in our age new events and
observations such that if Aristotle were now alive, I have no doubt he would
change his opinion. This is easily inferred from his own manner of
philosophizing, for when he writes of considering the heavens inalterable, etc.,
because no new thing is seen to be generated there or any old one dissolved, he
seems implicitly to let us understand that if he had seen any such event he would
have reversed his opinion, and properly preferred the sensible experience to
natural reason. Unless he had taken the senses into account, he would not have
argued immutability from sensible mutations not being seen.
SIMP. Aristotle first laid the basis of his argument a priori, showing the
necessity of the inalterability of heaven by means of natural, evident, and clear
principles. He afterward supported the same a posteriori, by the senses and by
the traditions of the ancients.
SALV. What you refer to is the method he uses in writing his doctrine, but I do
not believe it to be that with which he investigated it. Rather, I think it
certain that he first obtained it by means of the senses, experiments, and
observations, to assure himself as much as possible of his conclusions. Afterward
he sought means to make them demonstrable. That is what is done for the most part
in the demonstrative sciences; this comes about because when the conclusion is
true, one may by making use of analytical methods hit upon some proposition which
is already demonstrated, or arrive at some axiomatic principle; but if the
conclusion is false, one can go on forever without ever finding any known
truth -- if indeed one does not encounter some impossibility or manifest absurdity.
And you may be sure that Pythagoras, long before he discovered the proof for
which he sacrificed a hecatomb, was sure that the square on the side opposite the
right angle in a right triangle was equal to the squares on the other two sides.
The certainty of a conclusion assists not a little in the discovery of its
proof -- meaning always in the demonstrative sciences. But however Aristotle may
have proceeded, whether the reason a priori came before the sense perception a
posteriori or the other way round, it is enough that Aristotle, as he said many
times, preferred sensible experience to any argument. Besides, the strength of
the arguments a priori has already been examined.
Now, getting back to the subject, I say that things which are being and have been
discovered in the heavens in our own time are such that they can give entire
satisfaction to all philosophers, because just such events as we have been
calling generations and corruptions have been seen and are being seen in
particular bodies and in the whole expanse of heaven. Excellent astronomers have
observed many comets generated and dissipated in places above the lunar orbit,
besides the two new stars of 1572 and 1604, which were indisputably beyond all
the planets. And on the face of the sun itself, with the aid of the telescope,
they have seen produced and dissolved dense and dark matter, appearing much like the clouds upon the earth: and many of these are so vast as to exceed not only the Mediterranean Sea, but all of Africa,
with Asia thrown in. Now, if Aristotle had seen these things, what do you think
he would have said and done, Simplicio?
SIMP. I do not know what would have been done or said by Aristotle, who was the
master of all science, but I know to some extent what his followers do and say,
and what they ought to do and say in order not to remain without a guide, a
leader, and a chief in philosophy.
As to the comets, have not these modem astronomers who wanted to make them
celestial been vanquished by the Anti-Tycho? Vanquished, moreover, by their own weapons; that is, by means of parallaxes and of calculations turned about every
which way, and finally concluding in favor of Aristotle that they are all
elemental. A thing so fundamental to the innovators having been destroyed, what
more remains to keep them on their feet?
SALV. Calm yourself, Simplicio. What does this modem author of yours say about
the new stars of 1572 and 1604, and of the solar spots? As far as the comets are
concerned I, for my part, care little whether they are generated below or above
the moon, nor have I ever set much store by Tycho's verbosity. Neither do I feel
any reluctance to believe that their matter is elemental, and that they may rise
as they please without encountering any obstacle from the impenetrability of the
Peripatetic heavens, which I hold to be far more tenuous, yielding, and subtle
than our air. And as to the calculation of parallaxes, in the first place I doubt
whether comets are subject to parallax; besides, the inconstancy of the
observations upon which they have been computed renders me equally suspicious of
both his opinions and his adversary's -- the more so because it seems to me that the
Anti-Tycho sometimes trims to its author's taste those observations which do not
suit his purposes, or else declares them to be erroneous.
SIMP. With regard to the new stars, the Anti-Tycho thoroughly disposes of them in
a few words, saying that such recent new stars are not positively known to be
heavenly bodies, and that if its adversaries wish to prove any alterations and
generations in the latter, they must show us mutations made in stars which have
already been described for a long time and which are celestial objects beyond
doubt. And this can never possibly be done.
As to that material which some say is generated and dissolved on the face of the
sun, no mention is made of it at all, from which I should gather that the author
takes it for a fable, or for an illusion of the telescope, or at best for some phenomenon
produced by the air; in a word, for anything but celestial matter.
SALV. But you, Simplicio, what have you thought of to reply to the opposition of
these importunate spots which have come to disturb the heavens, and worse still,
the Peripatetic philosophy? It must be that you, as its intrepid defender, have
found a reply and a solution which you should not deprive us of.
SIMP. I have heard different opinions on this matter. Some say, "They are stars
which, like Venus and Mercury, go about the sun in their proper orbits, and in
passing under it present themselves to us as dark; and because there are many of
them, they frequently happen to collect together, and then again to separate."
Others believe them to be figments of the air; still others, illusions of the
lenses; and still others, other things. But I am most inclined to believe -- yes, I
think it certain -- that they are a collection of various different opaque objects, coming together almost
accidentally; and therefore we often see that in one spot there can be counted
ten or more such tiny bodies of irregular shape that look like snowflakes, or
tufts of wool, or flying moths. They change places with each other, now
separating and now congregating, but mostly right under the sun, about which, as
their center, they move. But it is not therefore necessary to say that they are
generated or decay. Rather, they are sometimes hidden behind the body of the sun;
at other times, though far from it, they cannot be seen because of their
proximity to its immeasurable light. For in the suns eccentric sphere
there is established a sort of onion composed of various folds,
one within another, each being studded with certain little spots, and moving; and
although their movements seem at first to be inconstant and irregular.
nonetheless it is said to be ultimately observed that after a certain time the
same spots are sure to return. This seems to me to be the most appropriate
expedient that has so far been found to account for such phenomena, and at the
same time to maintain the incorruptibility and ingenerability of the heavens. And
if this is not enough, there are more brilliant intellects who will find better
SALV. If what we are discussing were a point of law or of the humanities, in
which neither true nor false exists, one might trust in subtlety of mind and
readiness of tongue and in the greater experience of the writers, and expect him
who excelled in those things to make his reasoning
most plausible, and one might judge it to be the best. But in the natural
sciences, whose conclusions are true and necessary and have nothing to do with
human will, one must take care not to place oneself in the defense of error; for
here a thousand Demostheneses and a thousand Aristotles would be left in the
lurch by every mediocre wit who happened to hit upon the truth for himself
Therefore, Simplicio, give up this idea and this hope of yours that there may be
men so much more leaned, erudite, and well-read than the rest of us as to he able
to make that which is false become true in defiance of nature. And since among
all opinions that have thus far been produced regarding the essence of sunspots,
this one you have just explained appears to you to be the correct one, it follows
that all the rest are false. Now to free you also from that one -- which is an
utterly delusive chimera -- I shall, disregarding the many improbabilities in it,
convey to you but two observed facts against it.
One is that many of these spots are seen to originate in the middle of the solar
disc, and likewise many dissolve and vanish far from the edge of the sun, a
necessary argument that they must be generated and dissolved. For without
generation and corruption, they could appear there only by way of local motion,
and they all ought to enter and leave by the very edge.
The other observation, for those not in the rankest ignorance of perspective, is
that from the changes of shape observed in the spots, and from their apparent
changes in velocity, one must infer that the spots are in contact with the sun's
body, and that, touching its surface, they are moved either with it or upon it
and in no sense revolve in circles distant from it. Their motion proves this by
appearing to be very slow around the edge of the solar disc, and quite fast
toward its center; the shapes of the spots prove the same by appearing very
narrow around the sun's edge in comparison with how they look in the vicinity of
the center. For around the center they are seen in their majesty and as they really are; but around the edge, because of the
curvature of the spherical surface, they show themselves foreshortened. These
diminutions of both motion and shape, for anyone who knows how to observe them
and calculate diligently, correspond exactly to what ought to appear if the spots
are contiguous to the sun, and hopelessly contradict their moving in distant
circles, or even at small intervals from the solar body. This has been abundantly
demonstrated by our mutual friend in his Letters to Mark Welser on the Solar
Spots. It may be inferred from the same changes of shape that none of these are
stars or other spherical bodies, because of all shapes only the sphere is never
seen foreshortened, nor can it appear to be anything but perfectly round. So if
any of the individual spots were a round body, as all stars are deemed to be, it
would present the same roundness in the middle of the sun's disc as at the
extreme edge, whereas they so much foreshorten and look so thin near that
extremity, and &e on the other hand so broad and long toward the center, as to
make it certain that these are flakes of little thickness or depth with respect.
to their length and breadth.
Then as to its being observed ultimately that the same spots are sure to return
after a certain period, do not believe that, Simplicio; those who said that were
trying to deceive you. That this is so, you may see from their having said
nothing to you about those that are generated or dissolved on the face of the sun
far from the edge; nor told you a word about those which foreshorten, this being
a necessary proof of their contiguity to the sun. The truth about the same spots
returning is merely what is written in the said Letters; namely, that some of
them are occasionally of such long duration that they do not disappear in a
single revolution around the sun, which takes place in less than a month.
SIMP. To tell the truth, I have not made such long and careful
observations that I can qualify as an authority on the facts of this matter; but
certainly I wish to do so, and then to see whether I can once more succeed in
reconciling what experience presents to us with what Aristotle teaches. For
obviously two truths cannot contradict one another.
SALV. Whenever you wish to reconcile what your senses show you with the
soundest teachings of Aristotle, you will have no trouble at all. Does not
Aristotle say that because of the great distance, celestial matters cannot be
treated very definitely?
SIMP. He does say so, quite clearly.
SALV. Does he not also declare that what sensible experience shows ought
to be preferred over any argument, even one that seems to be extremely well
founded? And does he not say this positively and without a bit of hesitation?
SIMP. He does.
SALV. Then of the two propositions, both of them Aristotelian doctrines,
the second -- which says it is necessary to prefer the senses over arguments -- is a
more solid and definite doctrine than the other, which holds the heavens to be
inalterable. Therefore it is better Aristotelian philosophy to say "Heaven is
alterable because my senses tell me so," than to say, "Heaven is inalterable
because Aristotle was so persuaded by reasoning. Add to this that we possess a
better basis for reasoning about celestial things than Aristotle did. He admitted
such perceptions to be very difficult for him by reason of the distance from his
senses, and conceded that one whose senses could better represent them would be
able to philosophize about them with more certainty. Now we, thanks to the
telescope, have brought the heavens thirty or forty times closer to us than they
were to Aristotle, so that we can discern many things in them that he could not
see; among other things these sunspots, which were absolutely invisible to him.
Therefore we can treat of the heavens and the sun more confidently than Aristotle could.
SAGR. I can put myself in Simplicios place and see that he is deeply moved
by the overwhelming force of these conclusive arguments. But seeing on the other
hand the great authority that Aristotle has gained universally; considering the
number of famous interpreters who have toiled to explain his meanings; and
observing that the other sciences, so useful and necessary to mankind, base a
large pan of their value and reputation upon Aristotle's credit; Simplicio is
confused and perplexed, and I seem to hear him say, "Who would there be to settle
our controversies if Aristotle were to be deposed? What other author should we
follow in the schools, the academies, the universities? What philosopher has
written the whole of natural philosophy, so well arranged, without omitting a
single conclusion? Ought we to desert that structure under which so many
travelers have recuperated? Should we destroy that haven, that Prytaneum
where so many scholars have taken refuge so comfortably; where, without exposing
themselves to the inclemencies of the air, they can acquire a complete knowledge
of the universe by merely turning over a few pages? Should that fort be leveled
where one may abide in safety against all enemy assaults?"
I pity him no less than I should some fine gentleman who, having built a
magnificent palace at great trouble and expense, employing hundreds and hundreds
of artisans, and then beholding it threatened with ruin because of poor
foundations, should attempt, in order to avoid the grief of seeing the walls
destroyed, adorned as they are with so many lovely murals; or the columns fall,
which sustain the superb galleries, or the gilded beams; or the doors spoiled, or
the pediments and the marble cornices, brought in at so much cost -- should attempt,
I say, to prevent the collapse with chains, props, iron bars, buttresses, and
SALV. Well, Simplicio need not yet fear any such collapse; I undertake to
insure him against damage at a much smaller cost. There is no danger that such a
multitude of great, subtle, and wise philosophers will allow themselves to be
overcome by one or two who bluster a bit. Rather, without even directing their
pens against them, by means of silence alone, they place them in universal scorn
and derision. It is vanity to imagine that one can introduce a new philosophy by
refining this or that author, It is necessary first to teach the reform of the
human mind and to render it capable of distinguishing truth from falsehood, which
only God can do.
But where have we strayed, going from one argument to another? I shall not be
able to get back to the path without guidance from your memory.
SIMP. I remember quite well. We were dealing with the reply of the
Anti-Tycho to the objections against the immutability of the heavens. Among these
you brought in this mater of the sunspots, nqt mentioned by its author, and J
believe you wished to give consideration to his reply in the case of the new
SALV. Now I remember the rest. Continuing this subject, ii seems to me
that in the counter argument of the Anti-Tycho there are some things that ought
to be criticized. First of all, if the two new stars, which that author can do no
less than place in the highest regions of heaven, and which existed a long time
and finally vanished, caused him no anxiety about insisting upon the
inalterability of heaven simply because they were not unquestionably parts of
heaven or mutations in the ancient stars, then to what purpose does he make all
this fuss and bother about getting the comets away from the celestial regions at
all costs? Would it not have been enough for him to say that they are not
unques-tionably parts of heaven and not mutations in the ancient stars, and hence
that they do not prejudice in any way either the heavens or the doctrines of Aristotle?
In the second place I am not satisfied about his state of mind when he admits
that any alterations which might be made in the stars would be destructive of the
celestial prerogatives of incorruptibility, etc., since the stars are celestial
things, as is obvious and as everybody admits, and when on the other hand he is
not the least perturbed if the same alterations take place elsewhere in the
expanse of heaven outside the stars themselves. Does he perhaps mean to imply
that heaven is not a celestial thing? I should think that the stars were called
celestial things because of their being in the heavens, or because of their being
made of heavenly material, and that therefore the heavens would be even more
celestial than they; I could not say similarly that anything was more terrestrial
than earth itself, or more igneous than fire.
Next, his not having made mention of the sunspots, which are conclusively proved
to be produced and dissolved and to be situated next to the body of the sun and
to revolve with it or in relation to it, gives me a good indication that this
author may write more for the comforting of others than from his own convictions.
I say this because he shows himself to be acquainted with mathematics, and it
would be impossible for him not to be convinced by the proofs that such material
is necessarily contiguous to the sun and undergoes generations and dissolutions
so great that nothing of comparable size has ever occurred on earth. And if the
generations and corruptions occurring on the very globe of the sun are so many,
so great, and so frequent, while this can reasonably be called the noblest part
of the heavens, then what argument remains that can dissuade us from believing
that others take place on the other globes?
SAGR. I cannot without great astonishment -- I might say without great insult
to my intelligence -- hear it attributed as a prime perfection and nobility of the
natural and integral bodies of the universe that they are invariant, immutable,
inalterable, etc., while on the other hand it is called a great imperfection to
be alterable, generable, mutable, etc. For my part I consider the earth very
noble and admirable precisely because of the diverse alterations, changes,
generations, etc. that occur in it incessantly. If, not being subject to any
changes, it were a vast desert of sand or a mountain of jasper, or if at the time
of the flood the waters which covered it had frozen, and it had remained an
enormous globe of ice where nothing was ever born or ever altered or changed, I
should deem it a useless lump in the universe, devoid of activity and, in a word,
superfluous and essentially nonexistent. This is exactly the difference between a
living animal and a dead one; and I say the same of the moon, of Jupiter, and of
all other world globes.
The deeper I go in considering the vanities of popular reasoning, the lighter and
more foolish I find them. What greater stupidity can be imagined than that of
calling jewels, silver, and gold "precious," and earth and soil "base"? People
who do this ought to remember that if there were as great a scarcity of soil as
of jewels or precious metals, there would not be a prince who would not spend a
bushel of diamonds and rubies and a cartload of gold just to have enough earth to
plant a jasmine in a little pot, or to sow an orange seed and watch it sprout,
grow, and produce its handsome leaves, its fragrant flowers, and fine fruit. It
is scarcity and plenty that make the vulgar take things to be precious or
worthless; they call a diamond very beautiful because it is like pure water, and
then would not exchange one for ten barrels of water. Those who so greatly exalt
incorruptibility, inalterability, etc. are reduced to talking this way, I
believe, by their great desire to go on living, and by the terror they have of
death. They do not reflect that if men were immortal, they themselves would never
have come into the world. Such men really deserve to encounter a Medusa's head
which would transmute them into statues of jasper or of diamond, and thus make them more perfect than they are.
SALV. Maybe such a metamorphosis would not be entirely to their
disadvantage, for I think it would be better for them not to argue than to argue
on the wrong side.
SIMP. Oh, there is no doubt whatever that the earth is more perfect the
way it is, being alterable, changeable, etc., than it would be if it were a mass
of stone or even a solid diamond, and extremely hard and invariant. But to the
extent that these conditions bring nobility to the earth, they would render less
perfect the celestial bodies, in which they would be superfluous. For the
celestial bodies -- that is, the sun, the moon, and the other stars, Which are
ordained to have no other use than that of service to the earth -- need nothing more
than motion and light to achieve their end.
SAGR. Has nature, then, produced and directed all these enormous, perfect,
and most noble celestial bodies, invariant, eternal, and divine. for no other
purpose than to serve the changeable, transitory, and mortal earth? To serve that
which you call the dregs of the universe, the sink of all uncleanness? Now to
what purpose would the celestial bodies be made eternal, etc. in order to serve
something transitory, etc.? Take away this purpose of serving the earth, and the
innumerable host of celestial bodies is left useless and superfluous, since they
have not and cannot have any reciprocal activities among themselves, all of them
being inalterable, immutable, and invariant. For instance, if the moon is
invariant, how would you have the sun or any other star act upon it? The action
would doubtless have no more effect than an attempt to melt a large mass of gold
by looking at it or by thinking about it. Besides, it seems to me that at such
times as the celestial bodies are contributing to the generations and
alterations on the earth, they too must be alterable. Otherwise I do not see how
the influence of the moon or sun in causing generations on the earth would differ
from placing a marble statue beside a woman and expecting children from such a
SIMP. Corruptibility, alteration, mutation, etc. do not pertain to the
whole terrestrial globe, which as to its entirety is no less eternal than the sun
or moon. But as to its external parts it is generable and corruptible, and it is
certainly true that generations and corruptions are perpetual in those parts,
and, as perpetual, that they require celestial and eternal operations. Therefore
it is necessary that celestial bodies be eternal.
SAGR. This is all very well, but if there is nothing prejudicial to the
immortality of the entire terrestrial globe in the corruptibility of its
superficial pans, and if this generability, corruptibility, alterability, etc.
give to it a great ornament and perfection, then why can you not and should you
not likewise admit alterations, generations, etc. in the external parts of the
celestial globes, adding these as an ornament without diminishing their
perfection or depriving them of actions; even increasing those by making them
operative not only upon the earth but reciprocally among themselves, and the
earth also upon them?
SIMP. This cannot be, because the generations, mutations, etc. which would
occur, say, on the moon, would be vain and useless, and natura nihil frustra
SAGR. And why should they be vain and useless?
SIMP. Because we plainly see and feel that all generations, changes, etc.
that occur on earth are either directly or indirectly designed for the use,
comfort, and benefit of man. Horses are born to accommodate men; for the
nutriment of horses, the earth produces hay and the clouds water it. For the
comfort and nourishment of men are created herbs, cereals, fruits, beasts, birds,
and fishes. In brief, if we proceed to examine and weigh carefully all these
things, we shall find that the goal toward which all are directed is the need, the use, the comfort and the
delight of men. Now of what use to the human race could generations ever be which
might happen on the moon or other planets? Unless you mean that there are men
also on the moon who enjoy their fruits; an idea which if not mythical is
SAGR. I do not know nor do I suppose that herbs or plants or animals similar to
ours are propagated on the moon, or that rains and winds and thunderstorms occur
there as on the earth; much less that it is inhabited by men. Yet I still do not
see that it necessarily follows that since things similar to ours are not
generated there, no alterations at all take place, or that there cannot be things
there that do change or are generated and dissolve; things not only different
from ours, but so far from our conceptions as to be entirely unimaginable by us.
I am certain that a person born and raised in a huge forest among wild beasts and
birds, and knowing nothing of the watery element, would never be able to frame in
his imagination another world existing in nature differing from his, filled with
animals which would travel without legs or fast‹beating wings, and not upon its
surface alone like beasts upon the earth, but everywhere within its depths; and
not only moving, but stopping motionless wherever they pleased, a thing which
birds in the air cannot do. And that men lived there too, and built palaces and
cities, and traveled with such ease that without tiring themselves at all they
could proceed to far countries with their families and households and whole
cities. Now as I say, I am sure that such a man could not, even with the
liveliest imagination, ever picture to himself fishes, the ocean, ships, fleets,
and armadas. Thus, and more so, might it happen that in the moon, separated from
us by so much greater an interval and made of materials perhaps much different
from those on earth, substances exist and actions occur which are not merely
remote from but completely beyond all our imaginings, lacking any resem-blance to
ours and therefore being entirely unthinkable. For that which we imagine must be
either something already seen or a composite of things and parts of things seen
at different times; such are sphinxes, sirens, chimeras, centaurs, etc.
SALV. Many times have I given rein to my fancies about these things, and my
conclusion is that it is indeed possible to discover some things that do not and
cannot exist on the moon, but none which I believe can be and are there, except
very generally; that is, things occupying it, acting and moving in it, perhaps in
a very different way from ours, seeing and admiring the grandeur and beauty of
the universe and of its Maker and Director and continually singing encomiums in
His praise. I mean, in a word, doing what is so frequently decreed in the Holy
Scriptures; namely, a perpetual occupation of all creatures in praising God.
SAGR. These are among the things which, speaking very generally, could be there.
But I should like to hear you mention those which you believe cannot be there, as
it must be possible for you to name them more specifically.
SALV. I warn you, Sagredo, that this will be the third time we have thus strayed
imperceptibly, step by step, from our principal topic, and we shall get to the
point of our argument but slowly if we make digressions. Therefore it will
perhaps be good if we defer this matter, along with others we have agreed to put
off until a special session.
SAGR. Please, now that we are on the moon, let us go on with things that pertain
to it, so that we shall not have to make another trip over so long a road.
[pp. 71-113. Salviati, aided by Sagredo and relying greatly on data derived from the use
the telescope, expounds upon the moon's resemblance to the Earth: it is
spherical, dark, dense, mountainous; it is divided into areas of contrasting brightness, much like the land and sea areas, of the earth; from the moon the earth is seen to go through phases just
like the moon; the moon receives reflected sunlight from the earth, as the earth
does from the moon. Salviati also claims the moon always presents the same
hemisphere to the earth.
Simplicio disputes several points: he claims the moon is a perfectly smooth
sphere, of greater density than the earth because it is composed of celestial
material; while the moon is opaque, it is not dark, but rather polished to a
reflective luster like a mirror, it is impossible for the moon to receive any
light form the dark earth. The three engage in a lengthy argument about the moon,
involving in part a discussion of the properties of light and reflection, which
takes up most of the rest of this first day.]
SIMP. [Therefore, in your opinion, the earth would make an appearance similar to
that which we see in the moon, of at most two parts.] But do you believe then that
those great spots which are seen on the face of the moon are seas, and the
brighter balance land, or some such thing?
SALV. What you are now asking me is the first of the differences that I think
exist between the moon and the earth, which we had better hurry along with, as we
are staying too long on the moon. I say then that if there were in nature only
one way for two surfaces to be illuminated by the sun so that one appears lighter
than the other, and that this were by having one made of land and the other of
water, it would be necessary to say that the moon's surface was partly terrene
and partly aqueous. But because there are more ways known to us that could
produce the same effect, and perhaps others that we do not know of, I shall not
make bold to affirm one rather than another to exist on the moon.
We have already seen that a bleached silver plate changes from white to dark by
the touch of the burnisher; the watery part of the earth looks darker than the
dry; on the ridges of mountains the wooded parts look much gloomier than the open
and barren places because the plants cast a great deal of shadow while the
clearings are lighted by the sun. Such a mixture of shadows is so effective that
in sculptured velvet the color of the cut silk looks much darker than that of the
uncut, because of shadows cast between one thread and another; and plain velvet
is likewise much darker than taffeta made of the same silk. So if on the moon
there were things resembling dense forests, their aspect would probably be like
that of the spots we see; a like difference would be created if they were seas;
and, finally, there is nothing to prevent these spots being really of a darker
color than the rest, for it is in that way that snow makes mountains appear
What is clearly seen in the moon is that the darker parts are all plains, with
few rocks and ridges in them, though there are some. The brighter remainder is
all fill of rocks, mountains, round ridges, and other shapes, and in particular
there are great ranges of mountains around the spots. That the spots are flat
surfaces we are certain, from observing that the boundary which separates the
light and dark parts makes an even cut in traversing the spots, whereas in the
bright parts it looks broken and jagged. But I do not know whether this evenness
of surface is enough by itself to cause the apparent darkness, and I rather think
Quite apart from this, I consider the moon very different from the earth. Though
I fancy to myself that its regions are not idle and dead, still I do not assert
that life and motion exist there, and much less that plants, animals, or other
things similar to ours are generated there. Even if they were, they would be
extremely diverse, and far beyond all our imaginings. I am inclined to believe
this because in the first place I think that the material of the lunar globe is
not land and water, and this alone is enough to prevent generations and
alterations similar to ours. But even supposing land and water on the moon, there are in any case two reasons that
plants and animals similar to ours would not be produced there.
The first is that the varying aspects of the sun are so necessary for our various
species that these could not exist at all without them. Now the behavior of the
sun toward the earth is much different from that which it displays toward the
moon. As to daily illumination, we on the earth have for the most part twenty --
four hours divided between day and night, but the same effect takes a month on
the moon. The annual sinking and rising by which the sun causes the various
seasons and the inequalities of day and night are finished for the moon in a
month. And whereas for us the sun rises and sinks so much that between its
maximum and minimum altitudes there lie forty -- seven degrees of difference
(that is, as much as the distance between the tropics), for the moon it varies no
more than ten degrees or a little less, which is the amount of the maximum
latitudes of its orbit with respect to the ecliptic.
Now think what the action of the sun would be in the torrid zone if for fifteen
days without pause it continued to beat down with its rays. It goes without
saying that all the plants and herbs and animals would be destroyed; hence if any
species existed there, they would be plants and animals very different from
In the second place, I am sure that there are no rains on the moon, because if
clouds collected in any part of it, as around the earth, they would hide some of
the things on the moon that we see with the telescope. Briefly, the scene would
alter in some respect; an effect which I have never seen during long and diligent
observations, having always discovered a very pure and uniform serenity.
SAGR. To this it might be replied that either there might be great dews or that
it rains there during its nights; that is, when the sun does not light it up.
SALV. If from other appearances we had any signs that there were species similar
to ours there, and only the occurrence of rains was lacking, we should be able to
find this or some other condition to take their place, as happens in Egypt by the
inundations of the Nile. But finding no event whatever like ours, of the many
that would be required to produce similar effects, there is no point in troubling
to introduce one only, and even that one not from sure observation but because of
mere possibility. Besides, if I were asked what my basic knowledge and natural
reason told me regarding the production there of things similar to or different
from ours, I should always reply, "Very different and entirely unimaginable by
us"; for this seems to me to fit with the richness of nature and the omnipotence
of the Creator and Ruler.
SAGR. It always seems to me extreme rashness on the part of some when they want
to make human abilities the measure of what nature can do. On the contrary, there
is not a single effect in nature, even the least that exists, such that the most
ingenious theorists can arrive at a complete understanding of it. This vain
presumption of understanding everything can have no other basis than never
understanding anything. For anyone who had experienced just once the perfect
understanding of one single thing, and had truly tasted how knowledge is
accomplished, would recognize that of the infinity of other truths he understands
SALV. Your argument is quite conclusive; in confirmation of it we have the
evidence of those who do understand or have understood some thing; the more such
men have known, the more they have recognized and freely confessed their little
knowledge. And the wisest of the Greeks, so adjudged by the oracle, said openly
that he recognized that he knew nothing.
SIMP. It must be said, then, that either the oracle or Socrates himself was a
liar, the former declaring him the wisest, and the latter saying he knew himself
the most ignorant.
SALV. Neither of your alternatives follows, since both pronouncements can be
true. The oracle judges Socrates wisest above all other men, whose wisdom is
limited; Socrates recognizes his knowing nothing relative to absolute wisdom
which is infinite. And since much is the same part of infinite as little, or as
nothing (for to arrive at an infinite number it makes no difference whether we
accumulate thousands, tens, or zeros), Socrates did well to recognize his limited
knowledge to be as nothing to the infinity which he lacked. But since there is
nevertheless some knowledge to be found among men, and this is not equally
distributed to all, Socrates could have had a larger share than others and thus
have verified the response of the oracle.
SAGR. I think I understand this point quite well. Among men there exists the power
to act, Simplicio, but it is not equally shared by all; and no doubt the power of
an emperor is greater than that of a private person, but both are nil in
comparison to Divine omnipotence. Among men there are some who understand
agriculture better than others; but what has knowing how to plant a grapevine in
a ditch got to do with knowing how to make it take root, draw nourishment, take
from this some part good for building leaves, some other for forming tendrils,
this for the bunches, that for the grapes, the other for the skins, all this
being the work of most wise Nature? This is one single particular example of the
innumerable works of Nature, and in this alone may be recognized an infinite
wisdom; hence one may conclude that Divine wisdom is infinitely infinite.
SALV. Here is another example. Do we not say that the art of discovering a
beautiful statue in a block of marble has elevated the genius of Michelangelo
far, far above the ordinary minds of other men? Yet this work is nothing but the
copying of a single attitude and position of the external and superficial members
of one motionless man. Then what is it in comparison with a man made by Nature,
composed of so many members, external and internal, of so many muscles, tendons,
nerves, bones, that serve so many and such diverse motions? And what shall we say
of the senses, of spiritual power, and finally of the understanding? May we not
rightly say that the making of a statue yields by an infinite amount to the
formation of a live man, even to the formation of the lowest worm?
SAGR. And what difference do you think there was between the dove of Archytas and
a natural dove?
SIMP. Either I am without understanding or there is a manifest contradiction in
this argument of yours. Among your greatest encomiums, if not indeed the greatest
of all, is your praise for the understanding which you attribute to natural man.
A little while ago you agreed with Socrates that his understanding was nil. Then
you must say that not even Nature understood how to make an intellect that could
SALV. You put the point very sharply, and to answer the objection it is best to
have recourse to a philosophical distinction and to say that the human
understanding can be taken in two modes, the intensive or the extensive.
Extensively, that is, with regard to the multitude of intelligibles, which are
infinite, the human understanding is as nothing even if it understands a thousand
propositions; for a thousand in relation to infinity is zero. But taking man's
understanding intensively, in so far as this term denotes understanding some
proposition perfectly, I say that the human intellect does understand some of
them perfectly, and thus in these it has as much absolute certainty as Nature
itself has. Of such are the mathematical sciences alone; that is, geometry and
arithmetic, in which the Divine intellect indeed knows infinitely more
proposi-tions, since it knows all. But with regard to those few which the human
intellect does understand, I believe that its knowledge equals the Divine in
objective certainty, for here it succeeds in understanding necessity, beyond
which there can be no greater sureness.
SIMP. This speech strikes me as very bold and daring.
SALV. These are very ordinary propositions and far from any shade of temerity or
boldness. They do not detract in the least from the majesty of Divine wisdom,
just as saying that God cannot undo what is done does not in the least diminish
His omnipotence. But I question, Simplicio, whether your suspicion does not arise
from your having taken my words equivocally. So in order to explain myself
better, I say that as to the truth of the knowledge which is given by
mathematical proofs, this is the same that Divine wisdom recognizes; but I shall
concede to you indeed that the way in which God knows the infinite propositions
of which we know some few is exceedingly more excellent than ours. Our method
proceeds with reasoning by steps from one conclusion to another, while His is one
of simple intuition. We, for example, in order to win a knowledge of some
properties of the circle (which has an infinity of them), begin with one of the
simplest, and, taking this for the definition of circle, proceed by reasoning to
another property, and from this to a third, and then a fourth, and so on; but the
Divine intellect, by a simple apprehension of the circle's essence, knows without
time‹consuming reasoning all the infinity of its properties. Next, all these
properties are in effect virtually included in the definitions of all things; and
ultimately, through being infinite, are perhaps but one in their essence and in
the Divine mind. Nor is all the above entirely unknown to the human mind either,
but it is clouded with deep and thick mists, which become partly dispersed and
clarified when we master some conclusions and get them so firmly established and
so readily in our possession that we can run over them very rapidly. For, after
all, what more is there to the square on the hypotenuse being equal to the
squares on the other two sides, than the equality of two parallelograms on equal
bases and between parallel lines? And is this not ultimately the same as the
equality of two surfaces which when superimposed are not increased, but are
enclosed within the same boundaries? Now these advances, which our intellect
makes laboriously and step by step, run through the Divine mind like light in an
instant; which is the same as saying that everything is always present to it.
I conclude from this that our understanding, as well in the manner as in the
number of things understood, is infinitely surpassed by the Divine; but I do not
thereby abase it so much as to consider it absolutely null. No, when I consider
what marvelous things and how many of them men have understood, inquired into,
and contrived, I recognize and understand only too clearly that the human mind is
a work of God's, and one of the most excellent.
SAGR. I myself have many times considered in the same vein what you are now
saying, and how great may be the acuteness of the human mind. And when I run over
the many and marvelous inventions men have discovered in the arts as in letters,
and then reflect upon my own knowledge, I count myself little better than
miserable. I am so far from being able to promise myself, not indeed the finding
out of anything new, but even the learning of what has already been discovered,
that I feel stupid and confused, and am goaded by despair. If I look at some
excellent statue, I say within my heart: "When will you be able to remove the
excess from a block of marble and reveal so lovely a figure hidden therein? When
will you know how to mix different colors and spread them over a canvas or a wall
and represent all visible objects by their means, like a Michelangelo, a Raphael,
or a Titian?" Looking at what men have found out about ananging the musical
intervals and forming precepts and rules in order to control them for the wonderful delight of the ear, when shall I be
able to cease my amazement? What shall I say of so many and such diverse
instruments? With what admiration the reading of excellent poets fills anyone who
attentively studies the invention and interpreta-tion of concepts And what shall
I say of architecture? What of the art of navigation?
But surpassing all stupendous inventions, what sublimity of mind was his who
dreamed of finding means to communicate his deepest thoughts to any other person,
though distant by mighty intervals of place and time! Of talking with those who
are in India; of speaking to those who are not yet born and will not he born for
a thousand or ten thousand years; and with what facility, by the different
arrangements of twenty characters upon a page!
Let this be the seal of all the admirable inventions of mankind and the close of
our discussions for this day. The honest hours now being past, I think that
Salviati might like to enjoy our cool ones in a gondola; and tomorrow I shall
expect you both so that we may continue the discussions now begun.
End of the First Day
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