Key Arguments

• He distinguishes two senses of 'being in motion': one 'with reference to something else' (e.g. sailors moving only because the ship moves) and one 'intrinsically'; he then frames the question as whether the soul is moved 'intrinsically', thereby targeting the self‑motion thesis.
• He notes that there are four kinds of movement—'spatial movement, alteration, withering, and growth'—and insists that if the soul were moved, it would have to be moved by one or more of these standard physical movements, which already makes it look like a body or element.
• If the soul is moved non‑coincidentally (i.e. in its own right), 'place will so belong to it as well, since all the aforementioned sorts of movement occur at a place', which gives the soul a physical place contrary to its usual status as a non‑bodily principle.
• He contrasts this with coincidental movement in accidental attributes like 'the pale or the three cubits in length', which are moved only because the subject body is moved; these have 'no place belonging to them', whereas a soul that 'by nature participates in movement' would have a place of its own, which he implies is absurd.
• If the soul’s movement is natural, it must also be capable of forced movement and forced rest, since 'what something by nature moves toward, it also rests in by nature' and 'what it moves toward by force, it also rests in by force'; but 'what sorts of things forced movements and rests of the soul are, it is not at all easy to give an account of', showing the notion’s implausibility.
• If the soul has a natural upward or downward motion, it collapses into an elementary body—'if the natural movement of the soul is upward, it will be fire, if downward, earth, since these are the movements belonging to these bodies', and similarly for intermediate elements—undermining its distinctive status as soul.

Source Quotes

I 3 First we must investigate movement. For perhaps it is not merely false that the substance of the soul is the sort of thing that it is said to be by those who say that the soul is what moves—or is capable of moving—itself, | 406 a 1 | but rather for movement to belong to the soul is something impossible. Now, we said earlier that it is not necessary for what moves things to be itself moving.

Now, we said earlier that it is not necessary for what moves things to be itself moving. 63 For there are two ways in which anything can be moving—either with reference to something else or intrinsically. By “with reference to something else” I mean things that are moving because they are in | 406 a 5 | something that is moving—for example, sailors.

63 For there are two ways in which anything can be moving—either with reference to something else or intrinsically. By “with reference to something else” I mean things that are moving because they are in | 406 a 5 | something that is moving—for example, sailors. For they are not moving in the same way as the ship.

Since, then, things are said to be moving in these two ways, | 406 a 10 | we are now investigating about the soul whether it is moving, and participates in movement, intrinsically. There are four sorts of movement—spatial movement, alteration, withering, and growth. 64 It is, then, with one or more or all of these that the soul would move.

64 It is, then, with one or more or all of these that the soul would move. But if it is moved non-coincidentally, there would be a movement that belongs to it by nature, and, if this is so, | 406 a 15 | place will so belong to it as well, since all the aforementioned sorts of movement occur at a place. 65 But if the substance of soul is to move itself, movement will not belong to it coincidentally, as it does to the pale or the three cubits in length.

65 But if the substance of soul is to move itself, movement will not belong to it coincidentally, as it does to the pale or the three cubits in length. 66 For these are also moved, but coincidentally, since it is what they belong to that is moved, namely, the body. That is also why | 406 a 20 | they have no place belonging to them, whereas the soul will have a place, if indeed it by nature participates in movement. 67 Further, if it is moved by nature, it will also be moved by force, and if by force, then also by nature.

That is also why | 406 a 20 | they have no place belonging to them, whereas the soul will have a place, if indeed it by nature participates in movement. 67 Further, if it is moved by nature, it will also be moved by force, and if by force, then also by nature. 68 And it is the same way with rest as well.

Similarly, what it moves toward by force, it also rests in | 406 a 25 | by force. But what sorts of things forced movements and rests of the soul are, it is {10} not at all easy to give an account of, even if we wished to just fabricate one. Further, if the natural movement of the soul is upward, it will be fire, if downward, earth, since these are the movements belonging to these bodies.

But what sorts of things forced movements and rests of the soul are, it is {10} not at all easy to give an account of, even if we wished to just fabricate one. Further, if the natural movement of the soul is upward, it will be fire, if downward, earth, since these are the movements belonging to these bodies. 69 The same argument also applies to the intermediate ones. 70 Further, since it is evident that the soul moves the body, | 406 a 30 | it is quite reasonable to suppose that it moves it with the same movements with which it is itself moved.

Key Concepts

• First we must investigate movement. For perhaps it is not merely false that the substance of the soul is the sort of thing that it is said to be by those who say that the soul is what moves—or is capable of moving—itself, | 406 a 1 | but rather for movement to belong to the soul is something impossible.
• For there are two ways in which anything can be moving—either with reference to something else or intrinsically.
• By “with reference to something else” I mean things that are moving because they are in | 406 a 5 | something that is moving—for example, sailors.
• There are four sorts of movement—spatial movement, alteration, withering, and growth.
• if it is moved non-coincidentally, there would be a movement that belongs to it by nature, and, if this is so, | 406 a 15 | place will so belong to it as well, since all the aforementioned sorts of movement occur at a place.
• since it is what they belong to that is moved, namely, the body. That is also why | 406 a 20 | they have no place belonging to them, whereas the soul will have a place, if indeed it by nature participates in movement.
• Further, if it is moved by nature, it will also be moved by force, and if by force, then also by nature.
• what sorts of things forced movements and rests of the soul are, it is {10} not at all easy to give an account of, even if we wished to just fabricate one.
• if the natural movement of the soul is upward, it will be fire, if downward, earth, since these are the movements belonging to these bodies. 69 The same argument also applies to the intermediate ones.

Context

Beginning of I.3, where Aristotle shifts from surveying earlier doctrines to a direct critique of the thesis that the soul, in its substance, is a self‑mover or intrinsically moved.