"To every form of organic structure this definition applies, for even the parts of plants are organs, although very simple ones; thus the outer leaf is a protection to the pericarp, and the pericarp to the fruit. Or, again, the roots are organs bearing an analogy to the mouth in animals, both serving to take in food. Putting our definition, then, into a form applicable to every stage of the Vital principle, we shall say that _The Soul is the earliest realisation of a natural body having organisation_.
"In this way we are relieved from the necessity of asking whether Soul and body are one. We might as well ask whether the wax and the impression are one, or, in short, whether the _matter_ of any object and that whereof it is the matter or substratum are one. As has been pointed out, unity and substantiality may have several significations, but the truest sense of both is found in _realisation_.
"The general definition of the Soul or Vital principle above given may be further explained as follows. The Soul is the _rational_ substance (or function), that is to say, it is that which gives essential meaning and reality to a body as knowable. Thus if an axe were a _natural_ instrument or organ, its rational substance would be found in its realisation of what an axe means; this would be its _soul_. Apart { 206} from such realisation it would not be an axe at all, except in name. Being, however, such as it is, the axe remains an axe independently of any such realisation. For the statement that the Soul is the _reason_ of a thing, that which gives it essential meaning and reality, does not apply to such objects as an axe, but only to natural bodies having power of spontaneous motion (including growth) and rest.
"Or we may illustrate what has been said by reference to the bodily members. If the eye be a living creature, _sight_ will be its soul, for this is the _rational_ substance (or function) of the eye. On the other hand, the eye itself is the _material_ substance in which this function subsists, which function being gone, the eye would no longer be an eye, except in name, just as we can speak of the eye of a statue or of a painted form. Now apply this illustration from a part of the body to the whole. For as any one sense stands related to its organ, so does the vital sense in general to the whole sensitive organism as such, always remembering that we do not mean a dead body, but one which really has in it potential life, as the seed or fruit has. Of course there is a form of realisation to which the name applies in a specially full sense, as when the axe is actually cutting, the eye actually seeing, the man fully awake. But the Soul or Vital principle corresponds rather with the _function_ of sight, or the _capacity_ for cutting which { 207} the axe has, the body, on the other hand, standing in a relation of _potentiality_ to it. Now just as the eye may mean both the actual organ or pupil, and also the function of sight, so also the living creature means both the body and the soul. We cannot, therefore, think of body apart from soul, or soul apart from body. If, however, we regard the soul as composed of parts, we can see that the realisation to which we give the name of soul is in some cases essentially a realisation of certain parts of the body. We may, however, conceive the soul as in other aspects separable, in so far as the realisation cannot be connected with any bodily parts. Nay, we cannot be certain whether the soul may not be the realisation or perfection of the body as the sailor is of his boat."