and not separated, seeing that the faculty of perception has before it in one unity the distinct sense-perception, which by this means receives for the first time a determinate content. Another example is that of number; one and two are different, and, at the same time, even in two one is used and posited as one. γ. From sense-perception Aristotle passes on to thought, and becomes here really speculative. “Thinking,” he says (De Anima, III. 4) “is not passive (ἀπαθές), but receptive of the form, and is in potentiality similar to it. Therefore the understanding (νοῦς), because it thinks all things, is free from all admixture (ἀμιγής), in order that it may overcome (κρατῇ), as Anaxagoras says, that is, in order that it may acquire knowledge; for, coming forth in its energy (παρεμφαινόμενον), it holds back what is alien to it, and fortifies itself against it (ἀντιφράττει). Therefore the nature of the understanding is none other than this potentiality.” But potentiality itself is here not matter; that is to say, the understanding has no matter, for potentiality pertains to its very substance. For thinking is really the not being implicit; and on account of its purity its reality is not the being-for-another, but its potentiality is itself a being-for-self. A thing is real because it is this determinate thing; the opposite determination, its potentiality to be, for instance, smoke, ashes, and so on, is not posited in it. In the corporeal, therefore, matter, as potentiality, and external form, as reality, are opposed to one another; but the soul is, in contrast with this, universal potentiality itself, without matter, because its essence is energy. “Understanding, then, in the soul, as that which possesses consciousness, is nothing in reality before it thinks;” it is absolute activity, but exists only when it is active. “It is therefore not incorporated with the body. For what should it be like, warm or cold? Or should it be an organ? But it is none of these. That it is, however, different from the faculty of sense-perception is clear. For sense-perception cannot perceive after a violent perception; for instance, it cannot smell nor see after experiencing strong smells or colours. But the understanding, after it has thought something which can only be thought with difficulty, will not have more but less difficulty in thinking of something that is easier. For there is no sense-perception independent of the body, but the understanding is separable from it. When it has then become something individual, like him who is really possessed of a faculty of knowing (and this happens when he can energize through himself), it then is also in a certain degree according to potentiality, but yet not so in the same manner as it was before learning and finding.” (_Cf._ _supra_, pp. 182, 187.)