Lecture 3 — How, according to the Philosopher's opinion, the differences of position befit the parts of the heaven

236 Since we have already determined that functions of this kind belong to things which possess, a principle of movement, and that the heaven is animate and possesses a principle of movement, clearly the heaven must also exhibit above and below, right and left.

237 We need not be troubled by the question, arising from the spherical shape of the world, how there can be a distinction of right and left within it, all parts being alike and all for ever in motion.

238 We must think of the world as of something in which right differs from left in shape as well as in other respects, which subsequently is included in a sphere. The difference of function will persist, but will appear not to by reason of the regularity of shape.

239 In the same fashion must we conceive of the beginning of its movement. For even if it never began to move, yet it must possess a principle from which it would have begun to move if it had begun, and from which it would begin again if it came to a stand.

240 Now by its length I mean the interval between its poles, one pole being above and the other below;

241 for two hemispheres are specially distinguished from all others by the immobility of the poles.

242 Further, by 'transverse' in the universe we commonly mean, not above and below, but a direction crossing the line of the poles, which, by implication, is length: for transverse motion is motion crossing motion up and down.

243 Of the poles, that which we see above us is the lower region, and that which we do not see is the upper.

244 For right in anything is, as we say, the region in which locomotion originates, and the rotation of the heaven originates in the region from which the stars rise. So this will be the right, and the region where they set the left. If then they begin from the right and move round to the right, the upper must be the unseen pole. For if it is the pole we see, the movement will be leftward, which we deny to be the fact. Clearly then the invisible pole is above.

245 And those who live in the other hemisphere are above and to the right, while we are below and to the left. This is just the opposite of the view of the Pythagoreans, who make us above and on the right side and those in the other hemisphere below and on the left side; the fact being the exact opposite.

246 Relatively, however, to the secondary revolution, I mean that of the planets, we are above and on the right and they are below and on the left. For the principle of their movement has the reverse position, since the movement itself is the contrary of the other: hence it follows that we are at its beginning and they at its end.

Here we may end our discussion of the distinctions of parts created by the three dimensions and of the consequent differences of position.

313. After determining the question of the positional parts of the heaven according to the opinions of others, the Philosopher here discusses them according to his own opinion. As to this he does three things:

first, he shows that such positional differences must be in the heaven;

secondly, he explains which dimension determines "up" and "down" in the heaven, at now by its length (285b8; [320]);

thirdly, he shows which part of the heaven is up, and which is down, of the poles, that which we see above us (285b14; [323]).

About the first he does two things:

first he proves his proposition;

secondly, he excludes certain objections, at we need not be troubled (285a31; [317]).

314. With respect to the first he gives the following argument (285a27): it has been previously determined that in things possessing a principle of motion, namely, in living bodies which possess a moving principle within themselves, there are found such powers, i.e., differences of position according to the respective virtues in the parts, and not merely with respect to us, as in the case of non-living bodies which do not possess within themselves an active principle of motion but a passive one only, as is said in Physics VIII. But the heaven is animated and possesses a principle of motion.

That the heaven is animated he supposes from something proved in Physics VIII, namely, that all mobile beings must be reduced to one first self-mover that possesses its own active principle of motion and not merely its own passive principle, as some mentioned by Simplicius would claim. For they say that Aristotle called the heaven animate not because it had a rational soul but inasmuch as it had a kind of life implanted in its body in such a way, however, that the soul in it is nothing other than the nature of such a body. But that this is false is clearly shown by the words of Aristotle in Metaphysics XII to the effect that the first mover, which is completely immobile, moves the heaven as an object of thought and desire moves something. Consequently, it follows that, according to his opinion, the heaven is according to its soul something that desires and understands. And according to this, the motion of the heaven proceeds from its nature and from its soul: from its nature, indeed, as from a secondary and passive principle, inasmuch, namely, as such a body is apt to be moved in such a way; from its soul, however, as from a primary and active principle of motion.

315. Now in regard to this way of causing motion, it makes little difference whether the heaven is moved by a conjoined spiritual substance called its soul, or by a separated spiritual substance, except that a greater dignity accrues to the heaven if it is considered moved by a conjoined spiritual substance. This last consideration led Plato and Aristotle to posit an animated heaven. Someone could object, however, that although it is more noble for a body to have a spiritual substance conjoined to it, yet for the spiritual substance it is nobler to be separated from a body. For this reason Plato was led to say that it is for the good of the rational soul to be separated from the body at some time. Now according to this, since the mover is nobler than the moved and since motion depends more on the former, it seems better to say that the substance moving the heaven is separated from the body than to say that the heaven is animated; for this will give greater nobility to the motion of the heaven. Otherwise it would seem, following Plato's opinion, that the soul of the heaven would be in a worse condition than the human soul. But an answer to this could be that in one sense it is nobler for the human soul to exist outside the body than in the body, namely, to the extent that it moves the body with labor against its nature. But in respect to the natural existence of the soul it is better for the soul to be in the body, because through it the soul attains the perfect existence of its species. Consequently, if there be a spiritual substance whose power is determined to the motion of the heaven, which it moves without labor, as was said above, then for that substance it is nobler to be in such a body than to be separated; because the action is more perfect which is performed through a conjoined instrument than with a separated instrument. But a separated substance whose power is not determined to this effect is absolutely nobler.

Now from the fact that the heaven is animated, he concludes, in keeping with what was said, that it possesses an "up" and "down" as well as "right" and "left."

316. But this seems inappropriate. For he said previously that up and down belong to an animated body on account of growth, but front and behind on account of sense, and right and left on account of local motion. But no one who posits an animated heaven assumes for it either a motion of growth or a motion of sensation. Therefore, one should not posit an up and down in the heaven, or a front and behind. But it must be said that in perfect animals having local motion, these differences are considered not only with respect to growth and sense but also with respect to local motion. For which reason he said previously in one of his arguments that "up" is the originative source of motion, "right" is the terminus "from which," and front is the terminus "to which." But in things that lack local motion and have no right and left, their up and down, front and behind, are based on other motions. Consequently all these dimensions ought to be attributed to the heaven solely on the ground of local motion, as to a thing which is most perfect.

317. Then, at we need not be troubled (285a31), he excludes two objections.

The first of which is this: the heaven is spherical in shape; consequently all its parts are similar. But the aforesaid differences of position require dissimilarity of parts either in respect to power alone, as in the case of right and left, or in respect to shape as well, as in the case of up and down, front and behind, as was said above. Therefore it does not seem that these differences of position can be attributed to the heaven.

The second objection is that in animals where these various kinds of position are found, one part is moved before the other. But this cannot occur in the heaven, for its parts are always being moved, as he says in Physics VIII. Hence it seems that such positions are not to be attributed to the heaven.

318. Then, at we must think (285b1), he answers these objections, and first the first.

He says that this argument should not cause us to doubt our conclusion, but one should rather understand the case with the heaven as though it had a difference between right and left even according to a difference of shape in the parts, but later one should put a sphere around it, not exteriorly as a garment but as a body joined to it naturally and covering it exteriorly. Then what would be thus would in reality possess one power on the right and a different one on the left, although it would not appear to be so differentiated, on account of the similarity of shape which would outwardly appear. In like manner, from the soul of the heaven there are different powers in its several parts, although they are alike in shape. It is on account of this variety of powers that the aforesaid positions are attributed to the heaven.

319. Then, at in the same fashion (285b5), he answers the second objection and says that doubt should not arise from the fact that animals, in which these differences exist, possess a principle [or starting-point] of their motion. For even though the heaven never begins to be moved, yet, because its motion is orderly, it is necessary to consider something in its motion as a starting-point whence its motion would begin if it did begin, or whence its motion would resume, if it should happen to stop.

320. Then at now by its length (285b8) he explains which dimensions of the heaven are considered as up and down.

First he proposes what he intends, and says that the length of the heaven is the distance between its poles, namely, the arctic and antarctic, in such a way that one of these poles is up, and the other down.

321. Secondly, at for two hemispheres are specially distinguished (285b10) he proves this proposition in two ways.

First by reasoning. For it is plain that the length of any body is measured along its greatest dimension. Now the greatest dimension of a spherical body is diametric. But the diameter of the heaven is solely the one between the two poles, which are two immovable points of a sphere that never vary, whereas all other points taken are subject to motion. Consequently diameters drawn between any other two points are indeterminate. For this reason it is with respect to the line joining the two poles that the length of the heaven is considered, for inasmuch as these poles are not in motion, they allow us to see a definite difference of hemispheres.

322. Secondly, at further, by 'transverse' (285b11) he proves the same thing from the way people generally speak. For when we refer to the "sides" of the world, we do not mean the poles, which we call "up" and "down," but we mean something beside the poles, so that "east" is one side of the world, and "west" another, while the distance between the poles is the length of the heaven. For we call "side" what is adjoining "up" and "down" on either side, as is evident in man.

But it should be noted that for astronomers, who consider, not the dimensions of the heaven, but more the dimensions of the habitable earth, length is considered with respect to east and west, and width according to the distance from south to north—their reason being that the quantity of habitable earth from east to west is more than double that from pole to 'equator, since this is not fully inhabited.

323. Then, at of the poles, that which we see above us (285b14), he shows which of the poles is up and which down.

First he shows this with respect to the first motion;

secondly, with respect to the motion of the planets, at relatively, however (285; [329]).

As to the first he does three things:

first he proposes what he intends;

secondly, he proves what he has said, at for right (285b16; [324]);

thirdly, he draws a conclusion from this, at and those who live (285b23; [328]).

He says therefore first (285b14) that the pole which seems always to be over us is the downward part of the heaven, namely, the arctic pole; but the pole which is always hidden from us and called the antarctic is the part of the heaven referred to as up.

324. Then, at for right (285b16) he proves what he has said. Now it is manifest in the case of every animal that we call the "right" that which is the originative source of its local motion (on which account the right side of an animal is warmer, in order to be more apt for motion); but the circular motion of the heaven originates from that part whence the stars rise and which is called "east"; consequently the west will be its left. If, therefore, the motion of the heaven begins at the right and circulates back to the right, as though going from the same to the same, then necessarily the pole hidden from us, namely, the antarctic, is referred to as the upper part of the heavens, for if the arctic pole, which is never hidden from us, were the upper side, it would follow that the motion of the heaven would be from left to left. But this is not the way we speak of it. This will be easier to understand if we imagine a man with his head in the arctic and his feet in the antarctic poles of the heaven. His right hand will be in the west and his left in the east, provided his face is toward the upper hemisphere, i.e., the one visible to us on earth. Therefore, since the motion of the heaven is from east to west, it will follow that it is from the left to the right. On the other hand, if we place his head in the antarctic and his feet in the arctic pole, with his face as before, his right hand will be in the east and his left in the west. Then the motion would begin from the right, as it should. Thus it is clear that the heaven's "up" is the pole which is hidden from us.

325. But there are three objections to this. First it is objected that Aristotle fails to determine what is "front" and what is "behind" in the heaven. But it should be answered that he passed over this as clear from what he has already determined. For an animal's motion, beginning from its right, proceeds forward and not backward. Hence, since the heaven is moved from east to west toward the upper hemisphere (which is evident from the fact that the stars seem to climb after they rise), the consequence is that "front" in the heaven is the upper hemisphere and "behind" the lower hemisphere.

326. In the second place it is objected that, although it is always the same part of the animal that is its right and another same part which is always its left, this does not seem to be observed in the heaven: for the same part of the heaven that was in the east comes to be in the west; consequently, if the east is the right side and the left the west, the same part of the heaven will be the right at one time and the left at another time. But this is answered by something that Aristotle states in Physics VIII, namely, that the principle which moves the heaven is not moved per accidens as it is in animals. For these powers, according to which the aforesaid positions are attributed to animals, depend on the motive principle. Hence in animals that exist here the "right" power is moved per accidens when the body of the animal is moved. But in the heaven that power is understood to be immovably rigid, even though the parts of the heavenly body are moved. Therefore the "right" of the heaven is always in the east, no matter which single part of the heaven happens to be there. And the same holds for the other powers.

327. In the third place it is objected that east and west seem not to be definite parts of the heaven but to vary according to the horizon in each region. Consequently, if right and left are attributed respectively to the regions of rising and setting, right and left will not be determinate in the heavens according to themselves, as they are in the bodies of animals, but only in relation to us, as is the case with inanimate bodies. But it should be answered that, due to the immobility of the poles, up and down are said by him to be determinate in the heaven, while right and left are sides in relation to up and down. Therefore Aristotle is here taking rising and setting not in relation to our outlook but in relation to the immobile poles of the world.

328. Then, at and those who live (285b23) he concludes in the light of the foregoing to a difference as to the habitation of the earth. He says that since the hidden pole is up, those who live under that pole live in the upper hemisphere and on the right side of the heaven; but we who live on the other side of the earth are in the lower hemisphere and in the left side of the heaven. And this is contrary to the Pythagoreans, who held that we live in the upper direction and in the right side and the others in the downward direction and in the left side, while according to the foregoing the contrary happens.

Aristotle here seems to take "hemisphere's as that which results from dividing the heaven through the equinoxial circle [i.e., the equator] in a plane equidistant from the poles. From this it is plain that Aristotle is here saying that some men live or can live on the other side of the equator in a direction opposite to us. Now, if people are living or should live on the two quarters of earth that are distinguished from us by a circle intersecting the equator at right angles, passing through the equatorial poles, those people would be distinct from both of us, namely, who live above and below the equator, as people living on the rear of the heaven are distinct from the inhabitants of the fore part of the heaven, inasmuch as the motion of the heaven reaches them later, so that stars setting for us are rising for them and returning to the principle of motion, which is the right, when they are setting for them.

But since the right and left are equally distant on the side from the up and down, it seems improper to say that we who live under the arctic pole inhabit the nether and left side, while the others inhabit the upper and right side. To this it can be said that Aristotle spoke with respect to Greece in which he lived. Greece is indeed to the left inasmuch as it faces west and it is nether inasmuch as it is under the arctic pole. But since Aristotle seems here to speak in general for all the inhabitants in our habitat, it is better to say that he is speaking after the manner of Pythagoreans who referred right, up, and front, to the same thing, and the opposites to the same thing. According to this, Pythagoras considered that we live in the upper and right part. Or this could be according to perspective, because the arctic pole is directly above us, or better, looking to motions of the planets, as will be immediately evident..

329. Then, at relatively, however (285b28) he shows how these positions are distinguished according to the motions of the planets. And he says that with respect to the second circular motion, namely, that of the planets, we conversely, are up and to the right, while the people on the other side of the earth are down and to the left. For the principle of planetary motion is contrary (for they begin to be moved from the west). The reason for this difference is that the two motions are contrary, i.e., diverse, since contrariety, strictly speaking, is not found in a circular motion, as was explained in Book I. According to this, then, we live where the planet's motion begins and they live where it ends. Therefore those people seem to be stronger according to permanency, which is in the first motion; but we according to diversity of generation and corruption, which depend on the second motion, as will be explained later.

Finally, (285b33) he summarizes and says that we have said this much about the parts of the heaven, which are determined according to the dimensions of the heaven and according to place, but not according to the material parts of the heaven, as was said above.