LECTIO TWO

             § 584. Having shown that there are no more than five particular senses, the Philosopher next proceeds to ask whether these five senses spring from any one common potency. He is led to ask this by observing two activities which do not seem to be peculiar to any one sense, but to spring from some more general potency: for (a) we have some perception of the activities of the particular senses, e.g. we sense our own seeing and hearing; and (b) we distinguish between the objects proper to each of the different senses, between, for instance, sweet and white. So he enquires into the source of these two activities, first of the former, and then, at 'Each of the senses, then', of the latter. The former enquiry divides into three parts. First he states the problem, saying that the fact that we do perceive our own seeing and hearing and so forth implies either that sight (for example) is able to see its seeing, or that some other faculty has this power; and so also with the other senses.

             § 585. Next, at 'And if, etc.', he brings objections against both these alternatives. But first he proposes two arguments to show that it is sight that sees its own seeing. (1) If one perceives one's seeing by a sense other than sight, then either that sense is a sense of colour, or the sense of colour and the sense of seeing colour are quite distinct. But if one and the same sense knows colour and the sight of colour, then the act of one and the same sense bears at once upon the sight of colour and the coloured thing. Whence follows one of two consequences. For if this sense of seeing and of colour is not the sense of sight, then there are two senses with the same object, namely the coloured thing; but if it is the same as sight, then sight is, after all, what perceives seeing--which is contrary to the hypothesis. Nor could it possibly be maintained that the perception of seeing is not a perception of colour; without perceiving colour one cannot possibly perceive seeing, for seeing is only sensing colour.

             § 586. (2) The second argument begins at 'Further, if. . .', If the sense of seeing is other than sight, then the further question arises whether that sense of seeing also senses its own activity; and if it does not, then there must be a third sense which does this. And either this series goes on to infinity--which is impossible, both because no action could ever be completed which depended on an infinity of actions, and because no single subject can possess an infinite number of faculties--or we have to posit a sense which really does take account of itself, i.e. perceive its own sensation. But, by the same reasoning, there is no need to go beyond the first sense of all; there is no reason why sight should not sense its seeing. Therefore the sense of colour is the same as the sense of seeing colour.

             § 587. Then at 'Here is a problem' he puts an objection from the other side in the form of a difficulty, which he proceeds to answer at once, because he has already, with the arguments given above, gone a long way towards settling the whole question. The objection runs thus. If it is by sight that we sense our seeing, then we simply see our seeing. Now nothing is seen except colour or coloured things; if then one sees that one sees, the first seeing (that which is subsequently seen), must itself be coloured; which would seem to be false in view of the principle already laid down, that sight receives colour precisely in so far as it is colourless.

             § 588. Next, at 'It is clear then', he answers this difficulty in two ways. In the first place, it is clear from what has been said that to see can mean different things--a perception of our seeing and a perception of mere colour; and this gives two distinct senses of the word. To make this clearer, observe that when we say that we are seeing we sometimes mean that our sight is, at the present moment, actually being impressed by the visible object, namely colour; but we can also sometimes mean that we are aware of the difference between light and dark even when we are not, at the moment, receiving an impression from an exterior sensible object. But 'seeing' does not mean the same in both cases. So what this solution comes to is this, that the act of seeing can be regarded either as the disturbance of a sense-organ by an exterior sensible object, and in this sense colour only is seen; or as the act by which, after the said disturbance, and even on the disappearance of the sensible object, we form a judgement on the reception of the object into the sense-organ; and in this sense not only colour is seen, but also the sight of colour.

             § 589. Then, with 'Moreover, that which sees', he proposes his second answer to the difficulty. This answer is required by the fact that colour has two modes of being: a material mode in the object, a spiritual mode in sensation. The former solution implied only the first of these modes; this one depends on the second. And here he does three things: (1) he sets out the solution; (2) at 'If then there is movement' he proves what the solution assumes; (3) at 'Since the act' he applies it to the solution of certain other problems.

             § 590. First, then, he says that while one solution of the difficulty was found by maintaining that the subject seeing colour was not coloured, another might be argued on the assumption that the subject seeing colour is in a certain sense coloured, inasmuch as, in seeing, it takes in a likeness of colour, becoming like the coloured object. This is why the power by which one sees one's own seeing can still be strictly a power of sight. That the one who sees is, in a sense, coloured, he then proves from what was said above, i.e. that the sense-organ as such receives a form from the sensible object, but without matter; which is why, when the object passes away, we retain sensations and images, i.e. the appearances in and by which animals somehow sense things. So the one who sees becomes coloured in so far as he retains a likeness of colour and of the coloured thing; and not only sight, but any act of sense is identical in being with the act of the sensible object as such; although the mind can consider them apart.

             § 591. I say, the act of sense, meaning, for instance, actual hearing; and the act of the sensible object, meaning actual sound. For the two are not always in act: the hearer is not always hearing, nor the thing heard always sounding; but when the former goes into the appropriate act and the latter begins to sound, then together take place an actual sound and an actual hearing. Since, then, sight perceives an object and its actuality, and the one who sees is assimilated to the object, so that his act of seeing is the same being as the actuality of the object (though the mind can distinguish them), it follows that one and the same power in us sees colour, and the impression of colour on the sense-organ, and the visible actuality of the thing seen, and our sight of it. The power, then, by which we see our seeing is not really other than sight itself, though it can be thought of as distinct.

             § 592. (2) Next, where he says 'If then movement . . .', he proves his assumption that the sensible object and the sentient subject are actually identical though they can be thought of apart; making use here of Book III of the Physics, in which it is proved that movement and action and passion exist in that upon which the action in question bears, i.e. in the thing that is moved by and passive to the action. Now hearing is obviously passive with respect to sound. Therefore, the actual sound, no less than the actual hearing, exists on the side of the potency, in the organ of hearing; and this because the act of an active mover comes to full existence in what is passive to it, not in the agent as such. This is why it is not necessary that every mover be itself moved; for that is moved which has the movement; so that if the movement or action (which is a sort of movement) came to full existence in the mover, the mover would also be moved. And as in the Physics it was laid down that action and passion are one single actuality of the same subject, though they differ in thought, so here he says that the sensible object and sentient subject are actually identified in one subject, though they differ to thought. Hence the act of sound or of the sounding thing is the sensation of sound, while that of the hearer is hearing.

             § 593. For both hearing and sound can be regarded either as in act or as in potency; and what has been said of them in this connection is true also of the other senses and sensible objects, namely that, as the subject of both action and passion is not the agent but the thing that receives the action--the agent being only the source of the action--so the act of the sensible object, no less than the act of the sense-faculty, exists in the latter as in its subject. But sometimes a distinct word is used for each act, as when the act of the object is called 'sounding' and that of the faculty 'hearing'; while sometimes only the act of the faculty has a special name. Thus the act of sight is called vision, but that of colour is nameless; and the act of taste is called tasting, but that of savour has no name in Greek.

             § 594. Then (3) at 'Since the act', he uses the foregoing solution to answer two more questions. (a) Do the sense-faculty and its object together cease and together remain in being? Answering which, he observes that, since the actualities of faculty and object are one actuality in one subject, though distinct to thought (as has been said), therefore actual hearing and actual sounding must together cease to be and together persist; and so also with savour and tasting and the rest. But the same is not necessarily true of the faculties and objects as in potency.

             § 595. Which leads him to reject an opinion of some early natural philosophers. They were wrong, he says, in supposing that nothing was white or black except when it was seen; or had savour except when it was tasted; and so forth. And because they thought that nothing existed except what was sensible, and that the only knowing was sensation, they concluded that the whole being and truth of things was a mere appearance; and further, that contradictories could both be true at the same time, if and because they seemed true to different people.

             § 596. Now this is partly true and partly false. Sense-faculty and sense-object can be taken in two ways, as in potency and as in act. From the point of view of act, what they said was correct: there is no sense-object without sensation. But it is not true from the point of view of potency. They made 'assertions', i.e. without distinguishing, in a matter which calls for distinctions.

             § 597. Then, where he says 'Now if voice', he applies these principles to solve another problem: (b) why are certain objects, destructive of the senses, whilst others give them pleasure? And he says that since every harmonious and well-balanced sound is, as a sound, identical somehow with the faculty of hearing, the fact that the sound is a kind of harmony implies that hearing is the same. Now harmony or proportion is destroyed by excess; an excessive sense-object is therefore destructive of the faculty. An excessively sharp or heavy sound can destroy hearing; an excessively tasty thing destroys taste; too much brightness or darkness destroys the sight; over-powerful smells destroy the sense of smell. As though the sense itself in each case were a kind of proportion.

             § 598. On the other hand, if several sensible objects are mixed in due proportion the effect is pleasant. Thus savours mingled to a due sourness or sweetness or saltiness are extremely enjoyable. There is always more pleasure to be gained from combinations than from simplicity. Harmony is more enjoyable than mere high notes or mere low notes. So too in touch, with the combinations of hot and cold. For the sense-faculty delights in proportion as in its like, being itself a kind of proportion. But excess destroys it, or at least is disagreeable to it.

426b 8-427a 15

THE COMMON SENSE

             EACH OF THE SENSES, THEN, IS OF A SENSIBLE OBJECT and in a sense-organ, precisely as such, and it discerns the differences within its object--for example sight, black and white; taste, sweet and bitter; and likewise with the other senses.§§ 599-600

             Since we distinguish, however, between black and sweet, and any other of the sense-objects comparing them and perceiving that they differ, there must be some sense for this operation too; for these objects are all in the sense-order. Hence it is also clear that flesh is not the ultimate sense-organ; for, in that case, this discrimination would have to be effected by touching.§§ 601-2

             Nor could it be by divided [powers] that the sweet is discerned as other than the white: but both must be presented to some one faculty. For [otherwise] it would be like my perceiving one thing and you another: it would then certainly be evident that the two were different; but some one single [Power], must say that they differ--i.e. sweet from white. Therefore it is one single power that asserts this; and as it asserts, so it understands and senses. It is patent that it is not possible to distinguish separate objects by faculties themselves separate.§§ 603-4

             And the same holds with regard to separate points of time, as the following considerations show. For the faculty that says that good and bad differ says that they differ now, and this now is not extrinsic to the statement (I mean, as in saying now that they are different, but not that there is now a difference; whereas this [faculty] both says now and that the difference is now). Therefore they are discerned simultaneously; an undifferentiated principle distinguishes the two in an indivisible time.§ 605

             But it is impossible for one and the same thing, if indivisible, to be moved by contrary movements in an indivisible point of time. For if the object be sweet, it so affects the sense or the mind, but if bitter, contrariwise, and if white, in another way.§ 606

             Therefore [perhaps] what discriminates is numerically indivisible and inseparable, yet in essence distinct. For it is in one way capable of multiplicity because it perceives things divided off from one another: but in another way, it is indivisible. Thus in its essence indeed it is divisible, but it is indivisible locally and numerically.§ 607

             But this is not possible; one and the same indivisible thing can be in contrary states potentially, but not in its very essence. It can divide in its activities indeed; but it cannot be black and white at the same time; and therefore neither can it receive the forms of both--if this is how sensation and under- standing occur.§ 608

             But it is just as some speak of a point as one or as two, and in this sense as divisible. As indivisible [this faculty] is a unity making an instantaneous act of discernment. But as divisible, it is not a unity; for it uses the same point twice. In so far as it takes a third as two, it takes account of two objects which are distinct, as in a separate principle. Yet in so far as it is one, it acts instantaneously and by a single act.

             So much then by way of defining the principle by which we call any animal sentient.§§ 609-14