De Anima

We have to consider in the first place the subject of motion. For, unless I am mistaken, the definition of soul as the self-moving, or as that which is capable of self-motion, misrepresents its essential nature: nay, more; it is quite impossible for soul to have the attribute of motion at all. To begin with, it has been already stated that a thing may cause motion without necessarily being moved itself. A thing is always moved in one of two ways; that is, either indirectly,

through something else, or directly, of and through itself. We say things are moved through something else when they are in something else that is moved: as, for instance, sailors on board a ship: for they do not move in the same sense as the ship, for the ship moves of itself, they because they are in something else which is moved. This is evident if we consider the members of the body: for the motion proper to the feet and so to men also is walking, but it is not attributable to our sailors in the case supposed. There being thus two senses in which the term "to be moved" is used, we are now enquiring whether it is of and through itself that the soul is moved and partakes of motion.

Of motion there are four species, change of place or locomotion, change of quality or alteration, diminution and augmentation. It is, then, with one or more or all of these species that the soul will move. If it is not indirectly or per accidens that it moves, motion will be a natural attribute of soul; and, if this be so, it will also have position in space, since all the aforesaid species of motion are in space. But, if it be the essential nature of soul to move itself, motion will not be an accidental attribute of soul, as it is of whiteness or the length of three cubits; for these are also moved, but per accidens, viz. by the motion of the body to which these attributes belong. This, too, is why these attributes have no place belonging to them; but the soul will have a place, if indeed motion is its natural attribute.

Further, if it moves naturally, then it will also move under constraint; and, if under constraint, then also naturally. So likewise with rest. For, as it remains at rest naturally in any state into which it moves naturally, so similarly it remains at rest by constraint in any state into which it moves by constraint. But what is meant by constrained motions or states of rest of the soul it is not easy to explain, even though we give free play to fancy. Again, if its motion tends upward, it will be fire; if downward, earth; these being the motions proper to these natural bodies. And the same argument applies to directions of motion which are intermediate.

Again, since it appears that the soul sets the body in motion, it may reasonably be supposed to impart to it the motions which it has itself: and, if so, then conversely it is true to say that the motion which the soul has itself is the motion which the body

has. Now the motion of the body is motion in space: therefore the motion of the soul is also motion in space, whether the whole soul so move, or only the parts, the whole remaining at rest. But, if this is admissible, the soul might also conceivably quit the body and re-enter; and this would involve the consequence that dead animals may rise again.

To return now to motion per accidens, soul might certainly thus be moved by something external as well:—for the animal might be thrust by force. But a thing which has self-motion as part of its essential nature cannot be moved from without except incidentally; any more than that which is good in itself can be means to an end, or that which is good for its own sake can be so for the sake of something else. But, supposing the soul to be moved at all, one would say that sensible things would be the most likely to move it.

Again, even if soul does move itself, this is equivalent to saying that it is moved; and, all motion being defined as displacement of the thing moved, it will follow that the soul will be displaced from its own essential nature, if it be true that its self-movement is not an accident, but that motion belongs to the essence of soul in and of itself. Some say that the soul in fact moves the body, in which it is, in the same way in which it moves itself. So, for example, Democritus; and herein he resembled Philippus, the comic poet, who tells us that Daedalus endowed the wooden Aphrodite with motion, simply by pouring in quicksilver: this is very similar to what Democritus says. For according to him the spherical atoms, which from their nature can never remain still, being moved, tend to draw the whole body after them and thus set it in motion. But do these same atoms, we shall ask in our turn, produce rest, as well as motion? How this should be, it is difficult, if not impossible, to say. And, speaking generally, it is not in this way that the soul would seem to move the animal, but by means of purpose of some sort, that is, thought.

In the same way the Platonic Timaeus explains on physical grounds that the soul sets the body in motion, for by its own motion it sets the body also in motion, because it is closely interwoven with it. For when it had been made out of

the elements and divided in harmonical ratios in order that it might have a native perception of proportion and that the universe might move in harmonic revolutions, he, the creator, proceeded to bend the straight line into a circle; and then to split the one circle into two, intersecting at two points; and one of the two circles he split into seven, the revolutions of heaven being regarded as the motions of the soul. In the first place, it is not right to call the soul a magnitude. For by the soul of the universe Timaeus clearly intends something of the same sort as what is known as mind: he can hardly mean that it is like the sensitive or appetitive soul, whose movements are not circular. But the thinking mind is one and continuous in the same sense as the process of thinking. Now thinking consists of thoughts. But the unity of these thoughts is a unity of succession, the unity of a number, and not the unity of a magnitude. This being so, neither is mind continuous in this latter sense, but either it is without parts or else it is continuous in a different sense from an extended magnitude. For how can it possibly think if it be a magnitude? Will it think with some one or other of its parts: such parts being taken either in the sense of magnitudes or in the sense of points, if a point can be called a part? If it be with parts in the sense of points, and there is an. infinity of these, clearly mind will never reach the end of them; while, if they be taken in the sense of magnitudes, mind will have the same thoughts times without end. But experience shows that we can think a thought once and no more. Again, if it be enough for the soul to apprehend with one or other of its parts, what need is there for it to be moving in a circle or to have magnitude at all? But, if it is necessary to thought that the mind should bring the whole circle into contact, what does the contact of the several parts mean? Again, how will it think that which is divisible by means of that which is without parts, or that which is without parts by means of that which is divisible? It must be mind which is meant by the circle in question. For when mind moves it thinks; when a circle moves it revolves. If, then, thought is a revolution, the circle which has such a revolution must

be mind. But then it will go on thinking of something for ever, for this is required by the eternity of the revolution. To practical thinking there are limits, for it always implies an external end; while speculative thinking is determined in the same way as the logical explanations which express it. Now every explanation consists either in definition or in demonstration. But demonstrations have a premiss for starting-point and reach a kind of goal in the inference or conclusion; while, even if they never reach a conclusion, at all events they do not revert to the starting-point, but with the aid of a succession of middle terms and extremes advance in a straight line. But circular movement returns to the point from which it started. Definitions, too, are all determinate. Besides, if the same revolution recurs again and again, the mind will be obliged to think the same thing again and again. Further, it is a sort of rest or coming to a halt, and not motion, which thinking resembles: and we may say the same of the syllogism. Nor, again, will that which does not move easily, but under constraint, even realise happiness. If the motion of soul be not its essence, it will be an unnatural motion. And the entanglement of the mind in the body without the possibility of release is painful; nay, it is to be avoided, if indeed it is really better for mind to be independent of body, a view commonly expressed and widely accepted. Also it is not clear why the heaven revolves in a circle; seeing that circular motion is neither implied by the essence of soul (that form of movement being indeed merely accidental to it), nor due to the body: on the contrary it is rather the soul which causes the motion of the body. Besides, we are not even told that it is better so: yet surely the reason why God made the soul revolve in a circle ought to have been that movement was better for it than rest, and this form of movement better than any other.

But such an enquiry as this belongs more appropriately to a different subject: so let us dismiss it for the present. We may, however, note here another absurdity which is involved in this as in most other theories concerning the soul. They attach the soul to, and enclose it in, body, without further determining why this happens and what is the condition of the body. And yet some such explanation would seem to be required, as it is owing to their relationship that the

one acts, the other is acted upon, that the one is moved, and the other causes it to move; and between two things taken at random no such mutual relations exist. The supporters of such theories merely undertake to explain the nature of the soul. Of the body which is to receive it they have nothing more to say: just as if it were possible for any soul taken at random, according to the Pythagorean stories, to pass into any body. This is absurd, for each body appears to have a distinctive form or shape of its own. It is just like talking of a transmigration of carpentry into flutes: for the craft must employ the right tools and the soul the right body.