Summing up, therefore, we may say that the soul, like other entelechies, is consubstantial with its material substrate, the body. True it is more autonomous than are the inflexible entelechies of inorganic nature, inasmuch as it is independent of any given atom, molecule, or cell in the organic aggregate. Such a degree of freedom, for example, is not possessed by the most complex molecules, which show no other flexibility than tautomerism, even this small readjustment involving a change in their specificity. But this autonomy does not preclude the essential dependence of the soul upon the body. Generally speaking, the soul is incapable of existence apart from its total substrate, the organism. We say, _generally speaking_, because, as previously intimated, an exception must be made in the case of the _human soul_, which, being, as we shall see, a self-subsistent and spiritual entelechy, is by itself, apart from its material substrate, a sufficient subject of existence, and is therefore capable of surviving the dissolution of its complementary principle, the organism. Nevertheless, even in man, the soul forms one substance with the organism, and the organism participates as a coëfficient factor in all his vital functions, both physiological and psychic, excluding only the _superorganic_ or _spiritual_ functions of rational thought and volition, whose agent and recipient is the _soul alone_. In man, then, soul and body unite to form a single substance, a single nature, and a single person. Apart from the body, the human soul is, indeed, a complete entity, in the sense that it is capable of subsistence (independent existence), but, in another sense, it is not a complete entity, because apart from the body it cannot constitute a complete nature or complete personality. It is this essential incompleteness of the discarnate human soul that forms the natural basis of the Christian doctrine of the Resurrection of the Dead. Here, however, it is important to note the difference between the hylomorphic spiritualism of Aristotle and the psychophysical spiritualism of Descartes. By the latter _all_ conscious or physic functions are regarded as spiritual. The former, however, recognizes the fundamental difference which exists between the lower or animal, and the higher or rational functions of our conscious life. Sense-perception and sensual emotion belong to the former class, and must be regarded as _organic_ functions, whose agent and subject is neither the soul alone nor the organism alone, but the soul-informed organism or substantial composite of body and soul. Rational thinking and willing, on the contrary, are classified as _superorganic_ or _spiritual_ functions, inasmuch as they exclude the coägency of the organism and have the soul alone for their active cause and receptive subject.