LECTURE 4

IN ALTERATION AND IN INCREASE AND DECREASE THE MOVER AND THE MOVED ARE TOGETHER

             909. After he has shown in regard to local motion that the mover and the moved are together, he shows that the same thing is true of alteration; namely, that there is nothing intermediate between that which alters and that which is altered. He proves this first by induction. In all things which are altered it is clear that the ultimate thing which alters and the first thing which is altered are together.

             It seems, however, that this is difficult to see in certain alterations, as when the sun warms the air without warming the intermediate orbs of the planets; and as when a fish, caught in a net, benumbs the hands dragging the net without having the same effect on the net.

             But it must be said that things which are passive receive the action of things which are active according to their proper mode. Therefore, the intermediates which are between the first thing which alters and the ultimate thing which is altered undergo something from the first thing which alters, but perhaps not in the same manner as the ultimate thing which is altered. The net, therefore, suffers something from the benumbing fish, but not numbness, because it has no capacity for it. And the intermediate orbs of the planets receive something from the sun, namely light, but not heat.

             910. Secondly, where he says, 'Quality is altered . . .' (Appendix A, 694), he proves the same thing with an argument. The argument is as follows.

             Every alteration is similar to the alteration which occurs in respect to the senses. But in an alteration of the senses, the alterer and the thing altered are together. Therefore, this is true of every alteration. He proves the first point as follows. Every alteration occurs with respect to a sensible quality, which is the third species of quality. For bodies are altered with respect to these things in which bodies are primarily different from one another. These are the sensible qualities, as heaviness and lightness; hardness and softness, which are perceived by touch; sound and silence, which are perceived by hearing (but, nevertheless, if sound is taken in act, it is a quality in the air, and consequently a local motion; hence it does not seem with respect to a quality of this kind that there is alteration primarily and per se; but if sound is taken appropriately, then a thing becomes audible or not audible through an alteration); whiteness and blackness, which pertain to sight; sweet and bitter, which pertain to taste; wet and dry, density and rarity, which pertain to touch. And the same argument applies to their opposites and intermediates. And likewise there are other things which fall under the senses, like warmth and cold, and smoothness and roughness, which are also grasped by touch.

             Such things are passions contained under the genus of quality. They are called passions because they force a passion on the senses or because they are caused by passions, as is said in the Categories. They are called, moreover, 'passions of sensible bodies' because sensible bodies differ in respect to them insofar as one is warm and another cold, one is heavy and another light, and so forth, or insofar as one of the foregoing is in two things to a greater or lesser degree. For fire differs from water in respect to the difference of hot and cold, and from air in respect to greater and lesser heat. Furthermore, differences in sensible bodies occur insofar as they undergo one of these, though it may not be in them naturally. For example, we say that things which are heated differ from things which are cooled, and things which become sweet differ from things which become bitter, through some passion and not from nature.

             To be altered with respect to qualities of this kind happens to every sensible body, both animate and inanimate. In animate bodies certain parts are 'animated', that is, sensitive, as the eye and the hand, and other parts are 'not animated', that is, not sensitive, as hair and bones. Both types of parts are altered with respect to qualities of this kind, because the senses suffer in the act of sensing. For the actions of the senses, like hearing and vision, are motions through the body with some passion of the senses. For the senses do not have any action except through a bodily organ. And it is proper for a body to be moved and altered. Hence passion and alteration are more appropriately predicated of the senses rather than intellect, whose operation is not through a bodily organ.

             Thus it is clear that animate bodies are altered in respect to all the qualities and all the motions by which inanimate bodies are altered. But this statement cannot be converted. For in animate bodies there is found alteration in respect to the senses, which is not found in inanimate bodies. For inanimate bodies do not have knowledge of their alteration. Rather this is concealed from them. This would not be the case if they were altered in respect to sensation.

             And lest anyone think that it is impossible for a thing to be altered with respect to a sensible quality without sensing the alteration, he adds that not only is this true of inanimate things but it happens even to animate things. For nothing prevents even animate bodies from being unaware when they are altered. This happens when alteration occurs in such beings without an alteration of the senses, as when they are altered with respect to their non-sensitive parts.

             From this it is clear that if the passions of the senses are such that there is no intermediary between the agent and the patient, and if every alteration is through passions of this type by which the senses are altered, then it follows that the alterer introducing the passions and the thing altered undergoing them are together, and there is nothing intermediate between them.

             911. Next where he says, 'Moreover air is . . .' (Appendix A, 695), he proves the second point, namely, that in the alteration of the senses the alterer and the thing altered are together. For air is continuous with the sense, for example, sight, and is joined to it without an intermediary. And the visible body is continuous with the air. And the surface of a visible body, which is the subject of colour, is terminated at light, that is, at the illuminated air, which is terminated at sight. And so it is clear that the air which is altered and that which alters it are together, and similarly sight which is altered is together with the air which alters. And the same is true of hearing and smelling, if they are compared to that which moves primarily, that is, to the sensible body. For these sensations occur through an extrinsic medium. Taste and flavour are together for they are not joined through some extrinsic medium, and the same is true of touch. And in this way he maintains that in inanimate and insensible things the alterer and the thing altered are together.

             912. Next where he says, 'And that which is increased . . .' (Appendix A, 696), he proves the same thing in regard to the motion of increase and decrease. First he treats the motion of increase. That which is increased and the increaser must be together because increase is a kind of addition. Through the addition of some quantity a thing is increased. And the same is true of decrease, for the cause of decrease is the subtraction of some quantity.

             This proof may be understood in two ways. First one could say that the quantity which is added or subtracted is the proximate mover in these motions. For Aristotle says in De Anima, II, that flesh increases insofar as it is a quantity. And so it is clear that the moved is together with the mover. For a thing cannot be added to or subtracted from another if it is not together with it. This argument also deals with the principal agent. For every addition is a type of gathering, and subtraction is a type of separation. Moreover, it was shown above that in the motion of gathering and separating the mover and the moved are together. Hence it follows that this is also true of increase and decrease.

             And thus he finally concludes universally that there is no intermediary between the ultimate mover and the first thing moved.