Key Arguments

• He restates the general thesis: 'It has now been stated in universal terms what the soul is. For the soul is a substance in accord with the account. | 412 b 10 | And this is the essence of this sort of body.'
• He introduces the axe analogy: 'It is just like this: if an instrument—for example, an axe—were a natural body, its substance would be the being for the axe, and this would be its soul.'
• He then draws the homonymy consequence: 'And if this were separated from it, it would not still be an axe, except homonymously.' The mere material shape without the function does not really count as an axe.
• Similarly for the eye: 'For if the eye were an animal, sight would be its soul. For that is the substance of an eye, the one in accord with the account. And the eye is matter for sight, and if this fails, | 412 b 20 | it is no longer an eye, except homonymously, like an eye in stone or in a picture.'
• He insists that for truly natural bodies 'that has a starting-point of movement and rest within itself', it is this internal functional principle (soul) that is their essence, not any external form-giver.
• These analogies show concretely that 'soul' names the functional organization or 'being-for' of a body-part or organism, without which only an anatomical remnant remains.

Source Quotes

150 It has now been stated in universal terms what the soul is. For the soul is a substance in accord with the account. | 412 b 10 | And this is the essence of this sort of body. 151 It is just like this: if an instrument—for example, an axe—were a natural body, its substance would be the being for the axe, and this would be its soul.

For the soul is a substance in accord with the account. | 412 b 10 | And this is the essence of this sort of body. 151 It is just like this: if an instrument—for example, an axe—were a natural body, its substance would be the being for the axe, and this would be its soul. 152 And if this were separated from it, it would not still be an axe, except homonymously.

151 It is just like this: if an instrument—for example, an axe—were a natural body, its substance would be the being for the axe, and this would be its soul. 152 And if this were separated from it, it would not still be an axe, except homonymously. 153 As things stand, though, it is an axe.

153 As things stand, though, it is an axe. For it is not of this sort of body that the | 412 b 15 | essence and the account is the soul, but of a certain sort of natural body that has a starting-point of movement and rest within itself. We must get a theoretical grasp on how what has been said applies also in the case of the parts [of the body].

We must get a theoretical grasp on how what has been said applies also in the case of the parts [of the body]. For if the eye were an animal, sight would be its soul. For that is the substance of an eye, the one in accord with the account. And the eye is matter for sight, and if this fails, | 412 b 20 | it is no longer an eye, except homonymously, like an eye in stone or in a picture.

For that is the substance of an eye, the one in accord with the account. And the eye is matter for sight, and if this fails, | 412 b 20 | it is no longer an eye, except homonymously, like an eye in stone or in a picture. We must now apply what holds in the case of the part to the whole living body.

Key Concepts

• For the soul is a substance in accord with the account. | 412 b 10 | And this is the essence of this sort of body.
• It is just like this: if an instrument—for example, an axe—were a natural body, its substance would be the being for the axe, and this would be its soul.
• And if this were separated from it, it would not still be an axe, except homonymously.
• For it is not of this sort of body that the | 412 b 15 | essence and the account is the soul, but of a certain sort of natural body that has a starting-point of movement and rest within itself.
• For if the eye were an animal, sight would be its soul. For that is the substance of an eye, the one in accord with the account.
• And the eye is matter for sight, and if this fails, | 412 b 20 | it is no longer an eye, except homonymously, like an eye in stone or in a picture.

Context

Middle of II.1 (412b10–22), where Aristotle uses the examples of tools and sense-organs to explicate his abstract claim that soul is the essence or 'being-for' of a living body or part.