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Aristotle’s text in the De Anima


On the Soul, III, 4, 429a10-429b9


Turning now to the part of the soul with which the soul knows and thinks (whether this is separable from the others in definition only, or spatially as well) we have to inquire (1) what differentiates this part, and (2) how thinking can take place.

If thinking is like perceiving, it must be either a process in which the soul is acted upon by what is capable of being thought, or a process different from but analogous to that. The thinking part of the soul must therefore be, while impassible, capable of receiving the form of an object; that is, must be potentially identical in character with its object without being the object. Mind must be related to what is thinkable, as sense is to what is sensible.

Therefore, since everything is a possible object of thought, mind in order, as Anaxagoras says, to dominate, that is, to know, must be pure from all admixture; for the co-presence of what is alien to its nature is a hindrance and a block: it follows that it too, like the sensitive part, can have no nature of its own, other than that of having a certain capacity. Thus that in the soul which is called mind (by mind I mean that whereby the soul thinks and judges) is, before it thinks, not actually any real thing. For this reason it cannot reasonably be regarded as blended with the body: if so, it would acquire some quality, e.g. warmth or cold, or even have an organ like the sensitive faculty: as it is, it has none. It was a good idea to call the soul ‘the place of forms’, though (1) this description holds only of the intellective soul, and (2) even this is the forms only potentially, not actually.

Observation of the sense-organs and their employment reveals a distinction between the impassibility of the sensitive and that of the intellective faculty. After strong stimulation of a sense we are less able to exercise it than before, as e.g. in the case of a loud sound we cannot hear easily immediately after, or in the case of a bright colour or a powerful odour we cannot see or smell, but in the case of mind thought about an object that is highly intelligible renders it more and not less able afterwards to think objects that are less intelligible: the reason is that while the faculty of sensation is dependent upon the body, mind is separable from it.” (trad. by J. A. Smith)



Main passages of this text:

1)  Thinking is like perceiving: namely, (a) whatever thinks or perceives, while impassible, is capable of receiving the form of an object; (b) it is potentially similar in character with its object without being the object.

2)  Aristotle’s conclusion is that “intellect (nous)” is “pure from all admixture,” “cannot reasonably be regarded as blended with the body,” and “is separable from it.” The stress here is on being separable. [It is important to highlight that Aristotle’s conclusion does not concern the “person,” and not even the “soul” as such or the “human subject;” it just addresses what he calls “intellect”.]

3)  The main argument is that (a) “everything is a possible object of thought,” (b) so intellect must be pure “for the co-presence of what is alien to its nature is a hindrance and a block”.

4)  Supporting argument: the strong stimulation of the faculty of thought does not diminish the thinking ability; on the contrary, it increases it.


Terminological clarification: “impassible,” in Aristotle’s text, means that something is capable of receiving the form of something else without a substantial change in its own form (knowledge is an accidental change).


Something must be indeterminate in order to receive every kind of form. The analogy with the concept of “prime matter” can help. Prime matter, though, is not impassible. The analogy with sensory knowledge is helpful too. Sensory knowledge, though, can receive only bodily forms given by the images, and it is not perfectly impassible (see the fourth point about Aristotle’s text).



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