In man's soul, however, or rather in his intellect we find a form which combines in itself the peculiarities of sublunar as well as celestial forms. When in contact with the human body it partakes of the nature of other sublunar forms exhibiting its activity through matter and being inseparable from it. But it is not destroyed with the death of the body. It continues as a separate form after death. The soul, Aristotle defines as the first entelechy of the body. The term entelechy which sounds outlandish to us may be replaced by the word realization or actualization and is very close in meaning to the Aristotelian use of the word form. The soul then, according to Aristotle, is the realization or actualization or form of the body. The body takes the place of matter in the human composite. It has the composition and the structure which give it the capacity for performing the functions of a human being, as in any other composite, say an axe, the steel is the matter which has the potentiality or capacity of being made into a cutting instrument. Its cutting function is the form of the axe--we might almost say the soul of the axe, if it were not for the circumstance that it cannot do its own cutting; it must be wielded by someone else. So far then the human soul forms an inseparable unit with the body which it informs. As we do not think of the cutting function of an axe existing apart from the axe, so neither can we conceive of sensation, emotion or memory as existing without a body. In so far as the soul is this it is a material form like the rest, and ceases with the dissolution of the body. But the soul is more than this. It is also a thinking faculty. As such it is not in its essence dependent upon the body or any corporeal organ. It comes from without, having existed before the body, and it will continue to exist after the body is no more. That it is different from the sensitive soul is proven by the fact that the latter is inherent in the physical organ through which it acts, being the form of the body, as we have seen. And hence when an unusually violent stimulus, say a very bright light or a very loud sound, impinges upon the sense organ, the faculty of sight or hearing is injured to such an extent that it cannot thereafter perceive an ordinary sight or sound. But in the rational faculty this is not the case. The more intense the thought occupying the thinking soul, the more capable it becomes of thinking lesser thoughts. To be sure, the reason seems to weaken in old age, but this is due to the weakening of the body with which the soul is connected during life; the soul itself is just as active as ever.