"Among substances as above defined those are most truly such which we call bodily objects, and among these most especially objects which are the products of nature, inasmuch as all other bodies must be derived from them. Now among such natural objects some are possessed of life, some are not; by life I mean a process of spontaneous nourishment, growth, and decay. Every natural {204} object having life is a substance compounded, so to say, of several qualities. It is, in fact, a bodily substance defined in virtue of its having life. Between the living body thus defined and the Soul or Vital principle, a marked distinction must be drawn. The body cannot be said to 'subsist in' something else; rather must we say that it is the matter or substratum in which something else subsists. And what we mean by the soul is just this substance in the sense of the form or specific character that subsists in the natural body which is potentially living. In other words, the Soul is substance as realisation, only, however, of such a body as has just been defined. Recalling now the distinction between realisation as possessed knowledge and as actual contemplation, we shall see that in its essential nature the Soul or Vital principle corresponds rather with the first than with the second. For both sleep and waking depend on the Soul or Life being there, but of these waking only can be said to correspond with the active form of knowledge; sleep is rather to be compared with the state of having without being immediately conscious that we have. Now if we compare these two states in respect of their priority of development in a particular person, we shall see that the state of latent possession comes first. We may therefore define the Soul or Vital principle as The earliest {205} realisation (entelechy) of a natural body having in it the potentiality of life.
"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."
Observe that at the last Aristotle, though very tentatively, leaves an opening for immortality, where, as in the case of man, there are functions of the soul, such as philosophic contemplation, which cannot be related to bodily conditions. He really was convinced that in man there was a portion of that diviner aether which dwelt eternally in the heavens, and was the ever-moving cause of all things. If there was in man a passive mind, which became all things, as all things through sensation affected it, there was also, Aristotle argued, a creative mind in man, which is above, and unmixed with, that which it apprehends, {208} gives laws to this, is essentially prior to all particular knowledge, is therefore eternal, not subject to the conditions of time and space, consequently indestructible.
Finally, as a note on Aristotle's method, one may observe in this passage, first, Aristotle's use of 'defining examples,' the wax, the leaf and fruit, the axe, the eye, etc.; second, his practice of developing his distinctions gradually, Form and Matter in the abstract, then in substances of every kind, then in natural bodies, then in organic bodies of various grades, in separate organs, in the body as a whole, and in the Soul as separable in man; and thirdly, his method of approaching completeness in thought, by apparent contradictions or qualifications, which aim at meeting the complexity of nature by an equally organised complexity of analysis. To this let us simply add, by way of final characterisation, that in the preceding pages we have given but the merest fragment here and there of Aristotle's vast accomplishment. So wide is the range of his ken, so minute his observation, so subtle and complicated and allusive his illustrations, that it is doubtful if any student of his, through all the centuries in which he has influenced the world, ever found life long enough to fairly and fully grasp him. Meanwhile he retains his grasp upon us. Form and matter, final and efficient causes, potential and actual existences, {209} substance, accident, difference, genus, species, predication, syllogism, deduction, induction, analogy, and multitudes of other joints in the machinery of thought for all time, were forged for us in the workshop of Aristotle.
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