Part 26

[Sidenote: F] as Empedocles says! Earth had nothing to do with heat, water with wind; nothing heavy was found above, nothing light below; without commixture, without affection were the principles of all things, mere units, each desiring no intercourse with each or partnership, performing their separate scornful motions in mutual flight and aversion, a state of things which must always be, as Plato[325] teaches, where God is absent, the state of bodies deserted by intelligence and soul. So it was until the day when Providence brought Desire into Nature, and [Sidenote: 927] Friendship was engendered there, and Aphrodite, and Eros, as Empedocles tells us and Parmenides too and Hesiod,[326] so that things might change their places, and receive faculties from one another in turn, and, from being bound under stress, and forced, some to be in motion some to rest, might all begin to give in to the Better, instead of the Natural, and shift their places and so produce harmony and communion of the Whole.

XIII. ‘For if it be true that no other part of the universe departed from Nature, but that each rests in its natural place, not needing any transposition or rearrangement, and never from the first having needed any, I am at a loss to know what there is for Providence to do, or of what Zeus, “in art most excellent”,[327] is the maker and the artist-father. There would [Sidenote: B] be no need of tactics in an army if each soldier knew of himself how to take and keep place and post at the proper time; nor of gardeners or builders if the water of its own nature is to flow over the parts which need it, and moisten them, or if bricks and beams should of themselves adopt the movements and inclinations which are natural, and arrange themselves in their fitting places. If such a theory strike out Providence [Sidenote: C] altogether, and if it be God’s own attribute to order and discriminate things, what marvel is it that Nature has been so disposed and partitioned that fire is here and stars there, and again that earth is planted where it is and the moon above, each held by a firmer bond than that of Nature, the bond of Reason? Since, if all things are to observe natural tendencies, and to move each according to its nature, let the sun no longer go round in a circle, nor Phosphorus, nor any of the other stars, because it is the nature of light and fiery bodies to move upwards, not in a circle! But if Nature admits of such local variation as that fire, here seen to ascend, yet when it reaches heaven, joins in the general rotation, what marvel if heavy [Sidenote: D] and earthlike bodies too, when placed there, assume another kind of motion, mastered by the circumambient element? For it is not according to Nature that light things lose their upward tendency in heaven, and yet heaven cannot prevail over those which are heavy and incline downwards. No, heaven at some time had power to rearrange both these and those, and turned the nature of each to what was better.

XIV. ‘However, if we are at last to have done with notions enslaved to usage,[328] and to state fearlessly what appears to be true, it is probable that no part of a whole has any order, or position, or movement of its own which can be described in absolute terms as natural. But when each body places itself at the disposal of that on account of which it has come into being, [Sidenote: E] and in relation to which it naturally exists or has been created, to move as is useful and convenient to it, actively and passively and in all its own states conforming to the conservation, beauty, or power of that other, then, I hold, its place, movements and disposition are according to Nature. In man certainly, who has, if anything has, come into being according to Nature, [Sidenote: F] the heavy and earth-like parts are found above, mostly about the head, the hot and fiery in the middle regions; of the teeth one set grows from above, the other from below, yet neither contrary to Nature; nor can it be said of the fire in him that when it is above and flashes in his eyes it is natural, but when it is in stomach or heart, unnatural; each has been arranged as is proper and convenient.

_Mark well the tortoise and the trumpet-shell_,

says Empedocles, and, we may add, the nature of every shell-fish, and

_Earth uppermost, flesh under thou shalt see._

Yet the stony substance does not squeeze or crush the growth[329] [Sidenote: 928] within, nor again does the heat fly off and be lost because of its lightness; they are mingled and co-ordinated according to the nature of each.

XV. ‘And so it is probably with the universe, if it be indeed a living structure; in many places it contains earth, in many others fire, water, and wind, which are not forced out under stress, but arranged on a rational system. Take the eye; it is not where it is in the body owing to pressure acting on its light substance, nor has the heart fallen or slipped down [Sidenote: B] into the region of the chest because of its weight; each is arranged where it is because it was better so. Let us not then suppose that it is otherwise with the parts of the universe; that earth lies here where it has fallen of its own weight, that the sun, as Metrodorus of Chios used to think, has been pressed out into the upper region because of his lightness, like a bladder, or that the other stars have reached the places which they now hold as if they had been weighed in a balance and kicked the beam. No, the rational principle prevailed; and some, like eyes to give light, are inserted into the face of the Whole and revolve; the sun acts as a heart, and sheds and distributes out of himself heat and light, as it were blood and breath. [Sidenote: C] Earth and sea are to the universe, according to Nature, what stomach and bladder are to the animal. The moon, lying between sun and earth, as the liver or some other soft organ between heart and stomach, distributes here the gentle warmth from above, while she returns to us, digested, purified, and refined in her own sphere, the exhalations of earth. Whether her earth-like solid substance contributes to any other useful purposes, we cannot say. We do know that universally the Better prevails over the law of Stress. How can the view of the Stoics lead us to any probable result? That view is, that the luminous and subtle part of the atmosphere has by its rarity formed the [Sidenote: D] sky, the dense and consolidated part stars, and that, of the stars, the moon is the dullest and the grossest. However, we may see with our eyes that the moon is not entirely separated from the atmosphere, but moves within a great belt of it, having beneath itself a wind-swept region, where bodies are whirled, and amongst them comets. Thus these bodies have not been placed in the scales according to the weight or lightness of each, but have been arranged upon a different system.’

XVI. This said, as I was passing the turn to Lucius, the [Sidenote: E] argument now reaching the stage of demonstration, Aristotle said with a smile: ‘I protest that you have addressed your whole reply to those who assume that the moon herself is half fire, and who say of all bodies in common that they have an inclination of their own, some an upward one, some a downward. If there is a single person who holds that the stars move in a circle according to Nature, and are of a substance widely [Sidenote: F] different from the four elements, it has not occurred to our memory, even by accident; so that I am out of the discussion, and you also, Lucius.’ ‘No, no, good friend’, said Lucius. ‘As to the other stars, and the heaven in general, when your school asserts that they have a nature which is pure and transparent, and removed from all changes caused by passion, and when they introduce a circle of eternal[330] and never-ending revolution, perhaps no one would contradict you, at least for the present, although there are countless difficulties. But when the theory comes down and touches the moon, it no longer retains in her case the “freedom from passion” and the beauty of form of that body. Leaving out of account her other irregularities and points of difference, this very face which appears upon her has come there either from some passion proper to herself or by admixture of some other substance. [Sidenote: 929] Indeed, mixture implies some passion, since there is a loss of its own purity when a body is forcibly filled with what is inferior to itself. Consider her own torpor and dullness of speed, and her heat, so faint and ineffectual, wherein, as Ion[331] says—

_The black grape ripens not_;

to what are we to assign this, but to weakness in herself and passion, if passion can have place in an eternal and Olympian body? It comes to this, dear Aristotle; look on her as earth, and she appears a very beautiful object, venerable and highly adorned; but as star, or light, or any divine or heavenly body, I fear she may be found wanting in shapeliness and grace, and do no credit to her beautiful name, if out of all the multitude in heaven she alone goes round begging light of others, as Parmenides says, [Sidenote: B]

_For ever peering toward the sun’s bright rays._

Now when our comrade, in his dissertation, was expounding the proposition of Anaxagoras, that “the sun places the brightness in the moon”, he was highly applauded. But I am not going to speak of things which I learned from you or with you, I will gladly pass on to the remaining points. It is then probable that the moon is illuminated not as glass or crystal by the sunlight shining in and through her, nor yet by way of accumulation of light and rays, as torches when they multiply their light. For then we should have full moon at the beginning of the month just as much as at the middle, if she does not conceal or block the sun, but allows him[332] to pass through [Sidenote: C] because of her rarity, or if he, by way of commixture, shines upon the light around her and helps to kindle it with his own. For it is not possible to allege any bending or swerving aside on her part at the time of her conjunction, as we can when she is at the half, or is gibbous or crescent. Being then “plumb opposite”, as Democritus puts it, to her illuminant, she receives and admits the sun, so that we should expect to see her shining herself and also allowing him to shine through her. Now she is very far from doing this; she is herself invisible at those times, and she often hides him out of our sight.

_So from above for men_,

as Empedocles says, [Sidenote: D]

_She quenched his beams, shrouding a slice of earth Wide as the compass of the glancing moon_;

as though his light had fallen, not upon another star, but upon night and darkness.

‘The view of Posidonius, that it is because of the depth of the moon’s body that the light of the sun is not passed through to us, is wrong on the face of it. For the air, which is unlimited, and has a depth many times that of the moon, is filled throughout with sunlight and brightness. There is left then that of Empedocles, that the illumination which we get from the moon [Sidenote: E] arises in some way from the reflexion of the sun as he falls upon her. Hence her light reaches us without heat or lustre, whereas we should expect both if there were a kindling by him or a commixture of lights. But as voices return an echo weaker than the original sound, and missiles which glance off strike with weaker impact,

_E’en so the ray which smote the moon’s white orb_

reaches us in a feeble and exhausted stream, because the force is dispersed in the reflexion.’

XVII. Here Sylla broke in: ‘All these things no doubt [Sidenote: F] have their probabilities; but the strongest point on the other side was either explained away or it escaped our comrade’s attention; which was it?’

‘What do you mean?’ said Lucius. ‘The problem of the half-moon, I suppose?’

‘Precisely,’ said Sylla, ‘for as all reflexion takes place at equal angles, there is some reason in saying that when the moon is in mid-heaven at half-moon, the light is not carried from her on to the earth, but glances off beyond it; for the sun, being [Sidenote: 930] on the horizon, touches the moon with his rays, which will therefore, being reflected at equal angles, fall on the further side and beyond us, and will not send the light here; or else there will be a great distortion and variation in the angle, which is impossible.’

‘I assure you’, said Lucius, ‘that point was mentioned also;’ and here he glanced at Menelaus the mathematician, as he went on: ‘I am ashamed, dear Menelaus,’ he said, ‘in your presence to upset a mathematical assumption which is laid down as fundamental in all the Optics of Mirrors. But I feel obliged to say’, he continued, ‘that the law which requires reflexion in all cases to be at equal angles is neither self-evident [Sidenote: B] nor admitted. It is impugned in the instance of convex mirrors, when magnified images are reflected to the one point of sight. It is impugned also in that of double mirrors, when they are inclined towards one another so that there is an angle between them, and each surface returns a double image from one face, four images in all, two on the right, two on the left, two from the outer parts of the surfaces, two dimmer ones deep within the mirrors.[333] Plato[334] gives the cause why this takes place. He has told [Sidenote: C] us that if the mirrors be raised on either side, there is a gradual shifting of the visual reflexion as it passes from one side to the other. If then some images proceed directly to us, while others glance to the opposite side of the mirrors, and are returned thence to us, it is impossible that reflexion in all cases takes place at equal angles. They observe[335] that these images meet in one point, and further claim that the law of equal angles is disproved by the streams of light which actually proceed from the moon to the earth, holding the fact to be [Sidenote: D] far more convincing than the law. However, if we are so far to indulge the beloved geometry as to make her a present of this law, in the first place it may be expected to hold of mirrors which have been made accurately smooth. But the moon has many irregularities and rough parts, so that the rays proceeding from a large body, when they fall on considerable eminences, are exposed to counter-illuminations and reciprocal dispersion; the cross-light is reflected, involved, and accumulated as though it reached us from a number of mirrors. In the next place, even if we allow that the reflexions are produced at equal [Sidenote: E] angles upon the actual surface of the moon, yet, when the distance is so great, it is not impossible that the rays may be broken in their passage, or glance around, so that the light reaches us in one composite stream. Some go further, and show by a figure that many lights discharge their rays along a line inclined to the hypothenuse; but it was not possible to construct the diagram while speaking, especially before a large audience.[336]

XVIII. ‘Upon the whole question,’ he went on, ‘I am at a loss to see how they bring up the half-moon against us; the point fails equally upon her gibbous and crescent phases. For if the moon were a mass of air or fire which the sun illuminated, [Sidenote: F] he would not have left half her sphere always in shadow and darkness as seen by us; but even if he touched her in his circuit only in a small point, the proper consequence would follow, she would be affected all through, and her entire substance changed by the light penetrating everywhere with ease. When wine touches water on its extreme surface, or a drop of blood falls into liquid, the whole is discoloured at once, and turned to crimson. But the air itself, we are told, is not filled with sunshine by emanations or beams actually mingling with it, but by a change and alteration caused by something like a prick or touch. Now, how can they suppose that when star touches star or light light, it does not mingle with or alter the substance throughout, but only illuminates [Sidenote: 931] those points which it touches superficially? The circular orbit of the sun as he passes about the moon, which sometimes coincides with the line dividing her visible and invisible parts, and at other times rises to right angles with that line so as to cut those parts in two, and in turn be cut by her, produces her gibbous and crescent phases by the varying inclination and position of the bright part relatively to that in shadow. This proves beyond all question that the illumination is contact not commixture, not accumulation of light but its circumfusion. But the fact that she is not only illuminated herself but also sends [Sidenote: B] on the image of her brightness to us, allows us to insist the more confidently on our theory of her substance. For reflexions do not take place on a rarefied body, or one formed of subtle particles, nor is it easy to conceive light rebounding from light, or fire from fire; the body which is to produce recoil and reflexion must be heavy and dense, that there may be impact upon it and resilience from it. To the sun himself the air certainly allows a passage, offering no obstructions or resistance; whereas if timber, stones, or woven stuffs be placed to meet his light many cross rays are caused, and there is illumination all [Sidenote: C] round them. We see the same thing in the way his light reaches the earth. The earth does not pass his ray into a depth as water does, nor yet throughout her whole substance as air does. Just as his orbit passes round the moon, gradually cutting off a certain portion of her, so a similar orbit passes round the earth, illuminating a similar part of it and leaving another unilluminated, for the part of either body which receives light appears to be a little larger than a hemisphere. Allow me to speak geometrically in terms of proportion. Here are three bodies approached by the sun’s light, earth, moon, air; we see that the moon is illuminated like the earth, not like the air; but bodies naturally affected in the same way by the same must be themselves similar.’

XIX. When all had applauded Lucius, ‘Bravo!’ said I, [Sidenote: D] ‘a beautiful proportion fitted to a beautiful theory; for you must not be defrauded of your own.’ ‘In that case,’ he said, with a smile, ‘I must employ proportion a second time, in order that we may prove the moon like the earth, not only as being affected in the same way by the same body, but also as producing the same effect on the same. Grant me that no one of the phenomena relating to the sun is so like another as an eclipse to a sunset, remembering that recent concurrence[337] of sun and moon, which, beginning just after noon, showed us [Sidenote: E] plainly many stars in all parts of the heavens, and produced a chill in the temperature like that of twilight. If you have forgotten it, Theon here will bring up Mimnermus and Cydias, and Archilochus, and Stesichorus and Pindar[338] besides, all bewailing at eclipse time “the brightest star stolen from the sky” [Sidenote: F] and “night with us at midday”, speaking of the ray of the sun as “a track of darkness” and, besides all these, Homer[339] saying that the faces of men are “bound in night and gloom” and “the sun is perished out of the heaven”, i.e. around the moon, and how this occurs according to Nature, “when one moon perishes and one is born”. The remaining points have been reduced, I think, by the accuracy of mathematical methods to the one[340] certain principle that night is the shadow of earth, whereas an eclipse of the sun is the shadow of the moon when it falls within our vision. When the sun sets he is blocked from our sight by the earth; when he is eclipsed, by the moon. [Sidenote: 932] In both cases there is overshadowing; in his setting it is caused by the earth, in his eclipses by the moon, her shadow intercepting our vision. From all this it is easy to draw out a theory as to what happens. If the effect is similar, the agents are similar; for the same effects upon the same body must be due to the same agents. If the darkness of eclipses is not so profound, and does not affect the atmosphere so forcibly, let us not be surprised; the bodies which cause respectively night and eclipse are similar in nature, but unequal in size. The Egyptians, I believe, say that the moon’s bulk is one two-and-seventieth part of the earth’s, Anaxagoras made her as large as Peloponnesus; but [Sidenote: B] Aristarchus[341] proves that the diameter of the earth bears to that of the moon a ratio which is less than sixty to nineteen, and greater than a hundred and eight to forty-three. Hence the earth because of its size removes the sun entirely from our sight, the obstruction is great and lasts all night; whereas if the moon sometimes hides the sun entirely, yet the eclipse does not last long and has no breadth; but a certain brightness is apparent around the rim, which does not allow the shadow to be deep and absolute. Aristotle,[342] I mean the ancient philosopher, after giving other reasons why the moon is more [Sidenote: C] often visibly eclipsed than the sun, adds this further one, that the sun is eclipsed by the interposition of the moon,[343] [the moon by that of the earth and of other bodies also.] But Posidonius gives this definition of what occurs: an eclipse of the sun is a concurrence of the shadow of the moon with our vision[344] ... for there is no eclipse, except to those whose view of the sun can be intercepted by the shadow of the moon. In allowing that the shadow of the moon reaches to us, I do not know what he has left himself to say. There can be no shadow of a star; shadow means absence of light, and it is the nature of light to remove shadow, not to cause it.

XX. ‘But tell me’, he went on, ‘what proof was mentioned [Sidenote: D] next?’ ‘That the moon was eclipsed in the same way’, I said. ‘Thank you for reminding me’, he said. ‘But now am I to turn at once to the argument, assuming that you are satisfied, and allow that the moon is eclipsed when she is caught in the shadow, or do you wish me to set out a studied proof, with all the steps in order?’ ‘By all means,’ said Theon, ‘let us have the proof in full. For my own part, I still somehow need to be convinced; [Sidenote: E] I have only heard it put thus, that when the three bodies, earth, sun, and moon, come into one straight line eclipses occur, the earth removing the sun from the moon, or the moon the sun from the earth; that is, the sun is eclipsed when the moon, the moon when the earth, is in the middle of the three, the first case happening at her conjunction, the second at the half-month.’