LECTIO SIX

             § 299. After enumerating the powers of the soul and showing how the general definition given above is related to the particular divisions of soul, the Philosopher now explains what remains to be cleared up and in what order. There are, he says, still two points to be made clear, one of which links up with the argument just given. For we have seen that, just as we must not be satisfied with a completely general definition of soul, such as will not express any of its particular realisations, so too we cannot rest content even with a definition which does answer in some way to these latter; we must pursue our enquiry until we shall have defined precisely what is proper to each of these divisions of soul in particular. Whence it follows that we have to ask about each particular type of living being--plant or man or animal--what is its own particular life-principle; thus applying and particularising our common notion of soul.

             § 300. Then at 'It must be considered', he states the next point to be decided. He has already said that the parts of the soul follow each other in a series like the kinds of geometrical figure; and it remains to consider the reason for this. This reason will be given at the end of the Treatise; here he only shows how the parts of soul follow one from the other successively. The sensitive part, he says, cannot exist without the vegetative, but the latter can, in plants, exist without the sensitive. And this is not surprising; for, as we have seen, the purpose of the vegetative activities is to attain and retain existence itself, which is the ground of all the rest, as it were. And the senses display a like sequence; there are no senses at all unless there is touch; but touch itself can exist without the others. Many animals neither see, nor hear, nor smell, but only touch. And this will appear quite reasonable if we consider that by touch an animal is aware of the elements of which its substance consists (what it consists of and is nourished by), with which elements the other senses are only indirectly concerned. Hence the latter are not necessary for all animals, and in fact are found only in the higher animals.

             § 301. Again, there is the connection between sensitive and motive powers. Motive power cannot exist without sensitive, but the converse is not true. Some sentient beings move from place to place, but not all. We are speaking of the progressive movement of animals from one place to another; which is not found in all animals; though such as lack it show certain local movements of expansion and contraction--for instance, shellfish.

             The ultimate division of soul--and the least extensive since it is not subdivided into different species--is that which has the power of reason and understanding; because where reason exists in mortal beings, there also are found all the other aforesaid powers. He says 'mortal' to exclude immaterial substances and the heavenly bodies (if these are alive) which, as neither being born nor dying, do not need the vegetative power; and as being able to understand by a direct intuition of the intelligible object, do not require sense-knowledge as a preliminary condition of understanding; whereas in corruptible natures all the sub-intellectual powers are presupposed as instruments preparing the way for intellect, which is the final perfection of Nature. But these sub-intellectual powers do not necessarily imply reason in the subjects that possess them. And in view of the affinity between intellect and imagination (as he said above, intellect either is, or is accompanied by, imagination) he adds that some animals lack not only intellect but also imagination.

             § 302. Now this might seem to contradict a previous remark of his, that if a part cut from an animal retains sensation and desire, it retains also images -if the latter imply imagination, as seems likely. We must therefore say that (as will be shown in Book III) the lower animals have indeed a sort of imagination but indeterminately: i.e. the activity of imagining does not, in them, outlast actual sense-apprehension, as it does in the higher animals, which retain images of things sensed after these have been removed. Thus, as he says here, imagination varies in different animals. Some animals, lacking reason, live only by imagination, being led by it as we are led by reason. And though certain other animals lack both imagination and speculative intelligence, these two powers are not the same, as we shall see.

             Clearly, then, the definition of the soul which has been given applies very precisely to each part of the soul.

             § 303. Then, at 'It is necessary' he shows the order to be followed in examining the parts of soul. From one point of view, he explains, the first thing to do is to define the nature of each of these parts; and then consider 'habits', i.e. whatever other parts of soul derive from them, and anything else pertaining to them and to whatever they animate, such as the organs of the body and things of that kind. This procedure is necessary to avoid confusion.

             § 304. Then, at 'But if etc.', he observes that, from another point of view, our definition of any part of the soul--intellect or sensitivity or vegetativity--must begin from the act of the part in question, e.g. understanding or actual sensation; because in idea acts and operations precede potentialities. Potentiality is nothing but a capacity to act or be acted upon; it essentially involves a relation to actuality and can only be defined in such terms. And if this is the case with acts and potencies, acts in their turn connote something prior to themselves, i.e. their objects.

             § 305. For the type of every act or operation is determined by an object. Every operation of the soul is the act of a potentiality--either active or passive. Now the objects of passive potentialities stand to these as the causal agents which bring each potentiality into its proper activity; and it is thus that visible objects, and indeed all sensible things, are related to sight and to the other senses. But the objects of the active capacities are related to these as the final terms attained by their activities; for in this case the object is what each of these activities effectively realises. It is obvious that whenever an activity effectively realises anything besides the activity itself, the thing thus realised is the final term of the activity (cf. the Ethics, Book 1); for example a house is the final term of building. Hence all the objects of the soul's activities are either causal agents or final terms; and in both respects they specify those activities. For, obviously, specifically diverse causal agents do specifically diverse things--as heat heats and cold chills. And so also with the final term of activity: becoming well or becoming ill differ as 'doings', because health differs from illness. Thus in the work of seeking definitions we have to consider the objects of the soul's operations before these operations themselves.

             § 306. We ought, therefore, to reach conclusions about objects before activities for the same reason as leads us to define activities before potencies. The 'objects' in question are such things as food and sensible being and intelligible being, with respect to the vegetative, sensitive and intellectual faculties respectively.

             § 307. But note that the activities and powers of soul are not distinguished with respect to distinct objects except precisely in so far as these are objects. For instance, visible being differs from audible being precisely as object. But if there is no difference as object, then it does not matter what other differences there may be; they will not essentially affect the kind of activity or potentiality. Thus by the same faculty we see a coloured man and a coloured stone; the difference is merely incidental to the object of the faculty.

             § 308. Note too that our intellectual potency is, as such, only potentially intelligible; in order to be understood it must be actualised through an idea drawn from sensible images. A thing is knowable only in the degree that it is actual; hence our intellectual potency attains to self-knowledge only through possessing an intelligible object in a concept (as will be explained in Book III), and not by directly intuiting its own essence. This is why the process of self-knowledge has to start from the exterior things whence the mind draws the intelligible concepts in which it perceives itself; so we proceed from objects to acts, from acts to faculties, and from faculties to essence. But if the soul could know its essence in itself and directly it would be better to follow the reverse procedure; for in that case the closer anything was to the soul's essence, the more directly could it be known by the soul.

415a 23-415b 28

THE VEGETATIVE PRINCIPLE

HOW SOUL CAUSES BODY

             HENCE WE MUST FIRST SPEAK OF NUTRITION AND generation. For the vegetative soul is present in others, and is primary, and is that most general power of the soul by which life is present in anything: its operations being reproduction and the use of nutriment.§§ 309-10

             For the most natural of the operations of such living beings as are mature, and not defective nor spontaneously generated, is to produce others like themselves: an animal an animal, and a plant a plant. To this extent do they participate as far as they are able, in the imperishable and the divine. For this all things seek after, doing all that they do by nature for the sake of this. Now 'that for the sake of which' anything takes place, is twofold, one, the end 'for which', the other the end 'in which'. Since then they cannot share by a continuous being, in the divine and everlasting (since nothing corruptible remains for ever numerically one and the same) each shares in this as far as it is able, one, however, more, and another less. And thus it endures, not the same, but as if the same; one indeed, but in species, not numerically.§§ 311-17

             The soul is the cause and principle of the living body. Now these words can be used in many ways. The soul, however, is a cause in three established senses: for it is that whence comes movement; that 'for the sake of which'; and as the essence of living bodies.§ 318

             That it is as the essence is evident. For in all things, the essence is the cause of existence. In things that live, to live is to be; and the cause and principle of this is the soul.§ 319

             Further: of that which is in potency, the act is the [immanent] idea.§ 320

             It is manifest that the soul is also a cause 'for the sake of which'. For Nature operates for a purpose, in the same way as mind; and this is its end. Such is the soul in living things, according to Nature. For all natural bodies are instruments of the soul: whether of animals or of plants, they exist as for the sake of the soul. 'For the sake of' is a phrase used in two ways, as 'that for which', and 'that in which'.§§ 321-2

             But also the soul is the principle whence comes local motion. Yet this power is not present in all living things. Change and growth are, however, due to a soul, while sensation seems to be a kind of alteration, and nothing senses unless it has a soul. The same holds good of growth and decay; for nothing undergoes growth or decay physically, unless it is nourished; and nothing is nourished which does not share in life.§ 323