Lecture 14 — Indirect and direct proof that heavenly bodies do not produce sounds

304 From all this it is clear that the theory that the movement of the stars produces a harmony, i.e. that the sounds they make are concordant, in spite of the grace and originality with which it has been stated, is nevertheless untrue.

305 Some thinkers suppose that the motion of bodies of that size must produce a noise, since on our earth the motion of bodies far inferior in size and in speed of movement has that effect. Also, when the sun and the moon, they say, and all the stars, so great in number and in size, are moving with so rapid a motion, how should they not produce a sound immensely great?

306 Starting from this argument and from the observation that their speeds, as measured by their distances, are in the same ratios as musical concordances, they assert that the sound given forth by the circular movement of the stars is a harmony.

307 Since, however, it appears unaccountable that we should not hear this music,

308 they explain this by saying that the sound is in our ears from the very moment of birth and is thus indistinguishable from its contrary silence, since sound and silence are discriminated by mutual contrast. What happens to men, then, is just what happens to coppersmiths, who are so accustomed to the noise of the smithy that it makes no difference to them.

309 But, as we said before, melodious and poetical as the theory is, it cannot be a true account of the facts. There is not only the absurdity of our hearing nothing, the ground of which they try to remove, but also the fact that no effect other than sensitive is produced upon us. Excessive noises, we know, shatter the solid bodies even of inanimate things: the noise of thunder, for instance, splits rocks and the strongest of bodies. But if the moving bodies are so great, and the sound which penetrates to us is proportionate to their size, that sound must needs reach us in an intensity many times that of thunder, and the force of its action must be immense.

310 Indeed the reason why we do not hear, and show in our bodies none of the effects of violent force, is easily given: it is that there is no noise. But not only is the explanation evident; it is also a corroboration of the truth of the views we have advanced. For the very difficulty which made the Pythagoreans say that the motion of the stars produces a concord corroborates our view.

311 Bodies which are themselves in motion, produce noise and friction: but those which are attached or fixed to a moving body, as the parts to a ship, can no more create noise, than a ship on a river moving with the stream. Yet by the same argument one might say it was absurd that on a large vessel the motion of mast and poop should not make a great noise, and the like might be said of the movement of the vessel itself. But sound is caused when a moving body is enclosed in an unmoved body, and cannot be caused by one enclosed in, and continuous with, a moving body which creates no friction. We may say, then, in this matter that if the heavenly bodies moved in a generally diffused mass of air or fire, as every one supposes, their motion would necessarily cause a noise of tremendous strength and such a noise would necessarily reach and shatter us. Since, therefore, this effect is evidently not produced, it follows that none of them can move with the motion either of animate nature or of constraint.

312 It is as though nature had foreseen the result, that if their movement were other than it is, nothing on this earth could maintain its character.

313 That the stars are spherical and are not selfmoved, has now been explained.

420. After determining the matter of the motion of the stars, the Philosopher here treats of their sound, sound being an effect of local motion, as is said in On the Soul II. (Aristotle, On the Soul 2.8, 419b4–33.) Concerning this he does two things:

first he excludes the opinions of others;

secondly, he determines the truth, at indeed the reason why we do not hear (291a4; [428]).

Regarding the first he does three things:

first, he states his intention;

secondly, he presents the arguments of those who hold the opposite, some thinkers suppose (290b15; [421]);

thirdly, he shows how they try to account for a difficulty, at since, however, it appears unaccountable (290b24; [423]).

He says therefore first (290b12) that it is clear from what has been said (namely, that the stars are not moved), that if anyone asserts that a certain harmony, i.e., a harmonious sound, results from their motion as though the sounds of the stars harmonize with one another, such a one would be guilty both of levity for making assertions without sufficient reason, and of speaking superfluously. He says this on the ground that such a sound would not be advantageous to anything, but rather most harmful, as will be clear below. Moreover, the truth is otherwise, according to what has so far been demonstrated.

421. Then, at some thinkers suppose (290b15) he presents the argument proposed by the Pythagoreans who held the aforesaid opinion.

First he shows how they proved that the heavenly bodies produce a loud sound by their motion. For there are three things that seem to account for a loud sound made by bodies that are in motion among us, namely, such sounds are due to the size of the bodies that are in motion and to the velocity of their motion and to the number of bodies involved. Now the bodies that exist among us and cause sound have neither the size nor the speed of the sun and moon and other stars. This is evident in part from the fact that the sun and moon circle the whole world every day, and in part from what astronomy brings out about the sizes and the velocity of their motion. This is further confirmed by considering the great number of stars. Consequently there seems to be good reason why the sun and other stars should produce the greatest sounds in their course.

422. Secondly, at starting from this argument (290b21) he shows how they proved their sounds would produce a harmony. For it is evident from what is learned in music that swiftness of motion produces a sharp [high] sound, while slowness produces a grave [low] sound, Now a determinate proportion of high and low according to certain numbers is the cause of harmony in sounds—thus the ratio of 2 to 1 produces the diapason [octave]; the ratio of 3 to 2 produces the diapente [fifth] and so on for the others. Now it has been shown in what has gone before that the larger the circle in which a star is moved the greater is its speed, Such a circle for any given star is reckoned to be larger or smaller depending on its distance from the pole of that sphere in which the fixed stars are moved; while for a planet the size of its circle is reckoned from the center [of the universe]. Hence, according to the proportion of the distances of the stars between themselves, or from the center or the poles, they understood there to be a difference of speeds in the motions of the stars, and consequently, of high or low pitch in their sounds. For they found the elongation or distances to be according to numerical proportions, which produce musical harmonies. Therefore, said the Pythagoreans, the sound of the stars moving in their circuit is harmonious; and this sound they called a "voice," since they held the heavenly bodies to be animated.

423. Then, at since, however, it appears unaccountable (290b24) he shows how they met a certain difficulty.

First, therefore, he presents the difficulty: since we have hearing, by which we perceive sound, it does not seem reasonable that we should not hear such a loud voice if it were to proceed from the movement of the stars.

Secondly, at they explain this (290b25) he shows how they met this difficulty. For they asserted that the reason why we do not hear this voice is that, as soon as we are born, that sound co-exists with us, and therefore it cannot make itself noticeable by its opposite which is silence. For these two things, namely, the voice and silence are judged and discerned the one by the other. Hence, in relation to the sound of the heavenly bodies men are in a situation similar to the people who hammer on bronze and become so accustomed to it that, as it were, they do not perceive the difference between sound and silence, so filled with this sound do their ears become.

424. Thirdly, at but, as we said before (290b30) he attacks this explanation, declaring that as we said before, these statements are put forth by the Pythagoreans in an alluring manner, i.e., according to a certain probable argument that appeals to the ears of men, and musically, i.e., according to musical arguments, but without getting to the truth. For it is impossible that the reality be as they state. Because if heavenly bodies should make such great sounds, not only is it inconsistent that none of them is heard, which they try to solve, but also inconsistent that lower bodies do not suffer anything from these sounds, even though they do not perceive them. For we know that excessive sounds destroy not only the hearing of animals, but even certain inanimate objects—for example, the sound of thunder rends asunder stones and even harder bodies, such as iron, and buildings and the like. Now this happens not because inanimate bodies are affected by sound in the sense of something perceptible by hearing, but inasmuch as along with the sound, there is produced a violent striking and moving of the air, as the Philosopher says in On the Soul II. Since, therefore, heavenly bodies which are in motion, are of such great size, and since their sound, if produced, must be louder than thunder or any other sound, to a degree proportionate to their size, then certainly there is every reason that their sound should reach here and that there would be an unbearable power in the violence that it would do to lower bodies.

Their explanation is also plainly insufficient on yet another score, because continued exposure to strong sounds not only takes away the discernment of those sounds, but also that of others—as hammerers of bronze cannot distinguish other very slight sounds. Hence if it is through familiarity with them that we cannot hear the sounds of heavenly bodies, then for the same reason, we should not be able to hear any other sounds.

425. But, as Simplicius says in his Commentary, it seems that the position of Pythagoras can be maintained against the statements of Aristotle. First of all, because it can be said that the sounds of the heavenly bodies are not destructive but rather preservative and vivifying, just as the motion of the heaven is as a certain life for all things existing in nature, as is said in Physics VIII. Then, too, our failure to hear the sounds of heavenly bodies is not due to habit, as is said here, since the Pythagoreans claimed that Pythagoras at times heard this harmony, who, nevertheless, like others, was used to hearing it. But they say this occurred because not all sensible things are proportionate to all the senses, so as to be perceived by them—just as dogs perceive many odors that men cannot detect. In like manner, it can be said that those sounds are not perceptible to human hearing unless one have a sense uplifted and purified as did Pythagoras. It could also be said that Pythagoras heard such sounds not by hearing them but by knowing the proportions from which that harmony is formed.

426. But these explanations do not seem to contain the truth.

First, because we know that although heavenly bodies are the cause of life, and especially the sun, yet its brilliance harms our sight, whose proportion it exceeds. For the same reason a sound coming from the motion of those bodies would on account of its excessive power destroy our hearing.

Secondly, because, just as the intellect can perceive all intelligibles, so sensitivity can perceive all sensibles, for example, sight all that is visible and hearing all that is audible—wherefore in On the Soul III it is said that the soul is in a certain way all things according to sense and according to intellect. Hence if there were a hearing power that could not perceive any and every sound, then either the sound or the hearing would have to be called such only equivocally.

Now it can happen that some animal may take pleasure in some kind of sensible thing according to a particular sense that does not delight some other animal according to that sense. For example, man takes pleasure according to the olfactory sense in the odors of roses and lilies, but the other animals do not, for odors of this kind are found agreeable to men for themselves, whereas for other animals odors do not befit them or give them pleasure, except as referring to food; and the same is true for colors.

Also it can happen that an animal is unable to distinguish according to some sense the difference of some things because its sense is weak and because the object to be sensed is small. Thus, man, whose sense of smell is weak, cannot discern the difference between certain odors, for example, the odors of animals that are passing by, but dogs do. Yet if the odors were strong, men also could distinguish them.

Similarly, some animals according to the sense of sight gaze on the sun's brilliance, which the owl's eyes cannot stand, and avoid as destructive of its vision. Hence it would be impossible for such violent sounds to proceed from the movements of the heavenly bodies without being perceived by men or without harming their hearing; unless of course they are called sounds equivocally.

427. And that seems to be the opinion of Simplicius who is seen to dispute Alexander's statement that colors and all such things, should they exist in the heavenly bodies, are present in them as accidents and extraneous additions. Against this he says that to posit accidents and extraneous additions in the stars he considers as most unacceptable, since they have substantial and specific power. For it seemed to him that, because heavenly bodies are the cause of the substantial forms in lower things, no accident could exist in them. And according to this, since sensation is aware only of accidents, it would follow that we cannot sense anything of these bodies. Wherefore he asserts that we neither perceive the stars themselves, nor their size or figures, nor their surpassing beauties, nor their motion—the cause of their sound; all we see is their luster, as it were—just as, for example, the light of the sun is seen around the earth, but the sun itself is not seen.

But this is most expressly false. First of all because Aristotle in On the Soul II says: neither air nor water is transparent because it is air or water; they are transparent because each of them has contained in it a certain nature which is the same in both and is also found in the eternal and uppermost body. And for the same reason light, which is the actuality of the transparent, possesses the same nature in lower bodies and in heavenly bodies. If, therefore, these inferior bodies possess accidents that can be perceived by sense, then by the same token there exist in the heavenly bodies accidents perceptible to sense.

Furthermore, shape and size are mathematical things, whose notions are independent of that in which they may exist. Therefore, just as the shape and size of lower bodies are perceptible accidents, so too is this the case in heavenly bodies.

Moreover, this position would destroy all certitude of the science of astronomy which proceeds from what appears to our senses about heavenly bodies. Again, how could the motion of the heavenly bodies be their very substance, since motion is something most imperfect? This position would force us to say that, in the sun, shape, light, and motion were one and the same thing, since of one thing there is but one substance. Hence it is plain that it is wholly impossible for what he says to be. Now there is nothing to prevent heavenly bodies from having a specific power and there being at the same time certain accidents in them—for in the lower bodies there are certain accidental entities, although they have the power to generate things akin to them in kind.

428. Then, at indeed the reason why we do not hear (291a4) he determines the truth.

First he proposes what he intends;

secondly, he manifests his proposition, at bodies which are themselves (291a9; [429]).

He says, therefore, first, that it is reasonable that we do not hear the sound of heavenly bodies and that lower bodies are seen to suffer no violent effects from them—because they make no sound. Now the very argument that will explain the reason for this, i.e., why we do not hear the sounds of the heavenly bodies and why we suffer no violence from them, will at the same time confirm the truth of the previous statements, namely, to the effect that the stars have no motion of their own. For the problem raised by the Pythagoreans' teaching that a symphony, i.e., a musical harmony, resulted from the motion of the heavenly bodies, will serve as our argument that the stars are not moved on their own.

429. Then, at bodies which are themselves (291a9) he manifests his proposition.

First, with an argument taken from the efficient cause of sound;

secondly, with one taken from the final cause, at it is as though nature had foreseen (291a24; [430]).

He says therefore first (291a9) that whatever bodies among lower bodies are moved according to themselves, these produce a sound to the extent that they produce a blow, i.e., a percussion, of the air. But bodies that are not moved on their own, but are embedded, or in some way exist, in a locally moving body cannot cause sound, just as people seated in a boat do not cause a sound when the boat is moved, any more than do the parts of the boat firmly attached to the boat, unless because of the weakness of the joint, or when the ship is buffeted. Moreover, we do not perceive that any sound is made by a ship when it is carried along by the current of a river, i.e., when the ship's motion is due entirely to the flow of the water; however, if the motion of the ship is swifter than that of the water, then it will make a sound insofar as it cuts the water. Yet according to the very arguments by which the Pythagoreans asserted the heavenly bodies to make a sound, someone could say that it is inconsistent with this that the tree, i.e., the mast, of a ship, and the poop, while being so large, make no sound" or that the ship itself makes no sound when it is carried along by the current. We must, of course, understand that he is excluding the sound due to cutting the water, but not the sound, if any, due to the air being cut by the part of the ship above water. Such a sound is heard especially when the air resists in gusts of wind. But whatever is moved locally on its own—and not in some body which is carried along—without causing any percussion, cannot make a sound.

It must be said, therefore, that if the bodies of the stars were moved by themselves, whether in a great body of air, or whether we understand air as diffused through the whole universe, or whether in a great body of fire, as all those say who assign the highest place in bodies to fire, then the stars in their motion would have to make a sound greater than any natural sound. If that were so, it would follow that that sound would reach us here, and not only would it be heard by us, but it would corrupt the bodies which exist here. But because we do not see this happen, it follows that none of the stars is moved on its own, neither by a violent motion, nor by a motion proceeding from its soul. For the stars could not be moved on their own without dividing either the celestial spheres or some intermediate bodies. Now the spheres are moved on their own, yet they do not divide any body—hence no sound results from their movement. It is clear that, by what he says here, the Philosopher excludes the imagining of those holding that the stars are not moved in the spheres but in certain intermediate bodies, such as air or fire or something of that sort.

430. Then, at it is as though nature had foreseen (291a24) he shows the same thing from the final cause. For nature has endowed the stars with no motion of their own, and consequently with no sounds, as though foreseeing that unless the stars' motion should be such that they would not move of themselves, there would follow the undesirable consequence that nothing among lower things would be constant in itself, i.e., preserved for a certain space of time in its being.

One is given to understand by this, as Alexander notes, that Aristotle here feels that God exercises a providence over the things here below; for providence cannot be attributed to nature as it is a certain power in bodies, but only as it refers to a mind establishing nature.

In summing up he concludes (291a26) that we have said that the stars are spherical in shape and that they are not moved on their own.