quaintance with some special branch of knowledge which he is able to apply to actual use: and similarly the child as well as the grown-up man may be said to possess the 'capacity' to become a general. Now both of these capacities can be said to 'suffer' or be acted on: but the sense of this 'suffering' in the one case is very different from that which it bears in the other. The former, the man who possesses the capacity of knowledge simply in virtue of his humanity, 'suffers' or is acted on when from his condition of potential knowledge but actual ignorance he is brought round to the opposite condition, the other who possesses learning which he can apply is acted on by being led to give expression to the knowledge which he implicitly possesses. Thus in 'suffering' we must recognise two senseson the one hand, the destruction of the one state by its contrary (φθορά τις ὑπὸ τοῦ ἐναντίου), on the other hand a preservation of something potential by means of what is actual (σωτηρία τοῦ δυνάμει ὄντος ὑπὸ τοῦ ἐντελεχείᾳ ὄντος). We must accordingly distinguish between two kinds of 'suffering' in sense-perception -the first that in which the mere condition of a faculty becomes a faculty ready for action as happens at the time of birth (TÒ TOû yevvŵvтos), the second that which brings the perceptive faculty, when developed, into actual exercise and enables it to reach its natural termination.

Sense then is not merely the reaction to an outward stimulus: it is not simply a form of reflex action: it is rather the realization of an internal faculty in response to its appropriate object. The sensible object, is, in other words, not so much the condition as the occasion of sensation : perception is something internal and immanent; only called out into action by an external object. Thus, to take a definite example, taste is affected by the object of taste as touch: and therefore the organ of taste must be rendered moist and like its objects-yet this however without losing its intrinsic character (owoμevov). The view therefore of earlier thinkers who maintained that in sense-perception like was

1 11. 10, 42301: πάσχει γάρ τι ἡ γεῦσις ὑπὸ τοῦ γευστοῦ ᾗ γευστόν· ἀναγκαῖον ἄρα

affected by like is not altogether false when stated with the proper limitations. The faculty of sense is potentially that which the object of sense is in actuality: and thus while undergoing the impression it is like its object, but, after the impression has been received, it becomes identical with it'.

The object and the faculty of sense thus stand, to Aristotle's mind, in intimate relation with one another. The object and the faculty are in fact correlatives, and in the perceptive act tend to coincide. They differ only in the manner of their definite existence (T eiva) or in the manner in which they may be regarded (Toy). They are only different sides or aspects of one and the same phenomenon, one side of which expresses itself in the operations of sense, the other in the concrete sensible thing. Aristotle however does not carry his doctrine of the relativity of knowledge so far as to deny the existence of a sensible world apart from sense-perception. "The early natural philosophers"-Democritus and Empedocles would seem to be intended-" were not right in holding that there was nothing. white or black apart from vision, and no flavour independently of taste." Their theory, he thinks, is true if understood in reference to actual perception, but not if taken to apply to sense as ♦ mere potentiality. Sense and things sensible are indeed correlative terms: but the faculty of sense is not so permanent in the relation as is the sensible object itself. The sensible object in fact, Aristotle holds, precedes the exercise of sense: the removal of the sensible object removes along with it the faculty of sense, while the faculty of sense does not simultaneously remove the sensible object. It would seem therefore that

ὑγρανθῆναι τὸ δυνάμενον μὲν ὑγραίνεσθαι σωζόμενον, μὴ ὑγρὸν δὲ, το γευστικὸν αἰσθητήριον.

1 II. 5, 41823.

12 III. 2, 42; 26: ἡ δὲ τοῦ αἰσθητοῦ ἐνέργεια καὶ τῆς αἰσθήσεως ἡ αὐτὴ μέν ἐστι καὶ μία, τὸ δ' εἶναι οὐ ταὐτὸν αὐταῖς.

3 426920: ἀλλ ̓ οἱ πρότερον φυσιολόγοι τοῦτο οὐ καλῶς ἔλεγον, οὐθὲν οἰόμενοι οὔτε λευκὸν οὔτε μέλαν εἶναι ἄνευ ὄψεως, οὐδὲ χυμὸν ἄνευ γεύσεως.

4 Categ. 5, 37: τὸ μὲν γὰρ αἰσθητὸν ἀναιρεθὲν συναναιρεῖ τὴν αἴσθησιν, ἡ δ ̓

though Aristotle never really probed the difficulties contained within the question whether the faculty or the object of sense is prior, and glided over it by his elastic distinction of a potential and a real capacity, he still held firmly to the view that senseperception perpetually involves a correspondence between the object and the organ of sensation, so that if upon the one hand the outward object may be said to make the sense to operate, there is another in which the sense creates for itself the object which it can perceive'. To Aristotle, therefore, we may say matter is not a "permanent possibility of sensation" realized in perception but sensation a permanent possibility of perceiving what as perceived is the realization of the sensitive capacities.

The correspondence which thus subsists between the object and the organ of perception meets with special recognition in the phraseology of Aristotle. Perception, it is said, requires that the cognitive subject should occupy a middle point (μeσórns) with reference to the objects of sensation. For the object of sense generally presents a pair of opposites-white and black, sweet and bitter, hot and cold-and sense must for the moment identify itself with one or other of them. But, in order to do so, it must itself be neither: it must occupy the middle point between the pairs of opposing qualities, so that it may be the better able to distinguish between them. For sense is essentially a critical faculty: its office is to distinguish between the qualities of objects: and to do so it must be itself equally removed from all these qualities. And αἴσθησις τὸ αἰσθητὸν οὐ συναναιρεῖ. The grounds on which these conclusions are made to rest imply a physical conception of aloenois, which is hardly in accordance with Aristotle's developed views upon this subject. The alc@nróv, it is said, is prior to αἴσθησις because αἴσθησις itself results from a composition of various αισθητά, such as fire and water. Cp. Metaph. T. 5, 1010 37.

1 De Sensu, 2, 438°22: τὸ γὰρ αἰσθητὸν ἐνεργεῖν ποιεῖ τὴν αἴσθησιν.

2 11. 11. 11, 42426: αισθήσεως οἷον μεσότητός τινος οὔσης τῆς ἐν τοῖς αἰσθητοῖς ἐναντιώσεως, καὶ διὰ τοῦτο κρίνει τὰ αἰσθητά, τὸ γὰρ μέσον κριτικόν· γίνεται γὰρ πρὸς ἑκάτερον αὐτῶν θάτερον τῶν ἄκρων.

3 11. 11. 2, 422°23: πᾶσα γὰρ αἴσθησις μιᾶς, ἐναντιώσεως εἶναι δοκεῖ, οἷον ὄψις λευκοῦ καὶ μέλανος.

+ An. Post. 11. 19, 9935 : ἔχει γὰρ δύναμιν σύμφυτον κριτικὴν ἣν καλοῦσιν αἴσθησιν.

hence it is that the sense is powerless in the presence of a quality which exceeds a certain limit. Excessive light destroys the organ of vision: excessive sounds whether they be too high or too low cannot be perceived: excessive objects of touch destroy life itself. And the reason in each case is the same. Strong light, strong odours, too high sounds-all destroy that equilibrium which sense-perception involves: the organ as an intermediate condition is no longer able to cope with the quality which falls outside the ordinary range to which the perceptive powers are adapted'.

The general character of sense-perception should now be tolerably evident. Sense, we have seen, is no merely material process it is, as Aristotle expresses it, a "movement of the soul through the body?" Thus, in Aristotle's psychology, even perception is a going beyond the immediate fact, if the expression be allowed. The object which it apprehends is perceived not in its individual character but in relation to its general idea. And thus the object of sense-perception as perceived is implicitly an universal it is, to use Aristotle's example, not Callias, but Callias as man that we perceive*.

The analysis of the special senses requires us to take into consideration three main points. These three are 1st the object, 2nd the organ, and 3rd the medium of sense-perception. The second of these evidently enters into our inquiry. Perception, we have already seen, is a process in which at once soul

1 II. 12. 3, 42428.

• De Somno, 2, 454q: ἡ δὲ λεγομένη αἴσθησις ὡς ἐνέργεια κίνησίς τις διὰ τοῦ σώματος τῆς ψυχῆς ἐστι. Prob. XI. 33, χωρισθεῖσα δ' αἴσθησις διανοίας καθάπερ ἀναίσθητον πόνον exe (quoted by Teichmüller Pract. Ver. 287). Cp. Plato, Philebus 34 A, Tò đè év évì πάθει τὴν ψυχὴν καὶ τὸ σῶμα κοινῇ γιγνόμενον κοινῇ καὶ κινεῖσθαι, ταύτην δ ̓ αὖ τὴν κίνησιν ὀνομάζων αἴσθησιν οὐκ ἀπὸ τρόπου φθέγγοι ἄν.

3 De An. II. 12, 424a22: ὁμοίως δὲ καὶ ἡ αἴσθησις ἑκάστου ὑπὸ τοῦ ἔχοντος χρῶμα ἢ χυμὸν ἢ ψόφον πάσχει ἀλλ ̓ οὐχ ἡ ἕκαστον ἐκείνων λέγεται, ἀλλ ̓ ᾗ τοιονδὶ καὶ κατὰ τὸν λόγον. Cp. Am. Post. I. 31, 87028, ἔστιν ἡ αἰσθησις τοῦ τοιοῦδε καὶ μὴ τοῦδέ τινος.

4 An. Post. II. 19, 100*16, καὶ γὰρ αἰσθάνεται μὲν τὸ καθ' ἕκαστον, αἴσθησις τοῦ καθόλου ἐστίν, οἷον ἀνθρώπου ἀλλ ̓ οὐ Καλλίου ἀνθρώπου.

!

and body are concerned, and it is therefore necessary to discuss the physical machinery by which perception is effected. The first-the object of sensation-calls for more remark. Aristotle it should be noted distinguishes between three kinds of objects of sense-a special, a common, and an incidental object'. It is the first of these three objects of sensation with which we have meanwhile to do. Each single sense, Aristotle holds, has a special quality assigned to it: and the sense as such never goes beyond this quality. Thus the object of sight, we shall find, is colour, the object of hearing sound: and thus sight never gets beyond perceiving colours, hearing beyond perceiving sounds: if we do go beyond it and refer our sensation to a thing or person, we have passed beyond the special sensible, and, interpreting our sensation, have reached what Aristotle calls the incidental object of sensation3. It is then only this special sensible-this idlov aloonτóv-with which we are meanwhile concerned, and with regard to each special sense our first inquiry (first, because, as we have seen, the object is prior to the faculty) must be—what is the object with which it is concerned. But not only have we to discuss the object and the organ: the perceptive act also involves a medium. The impression which effects perception is no actual contact between the object and the organ in fact, if the object be placed directly on the organ (e.g. the eye) no perceptive act whatever will result. Rather, perception is the result of a movement which is communicated by the object to some intervening substance, and is thence transmitted to the organ of perception. And thus it becomes an essential part of an analysis into the separate senses to inquire what is the nature of the media by which the sensible quality, which is the real object of sensation, is transmitted to the organ of perception.

1

II. 6.

2 11. 6, 41811: λέγω δ ̓ ἴδιον μὲν ὁ μὴ ἐνδέχεται ἑτέρᾳ αἰσθήσει αἰσθάνεσθαι, οἷον ὄψις χρώματος. Cp. Plato, Theaetetus 184 E: ἦ καὶ ἐθελήσεις ὁμολογεῖν ἃ δι' ἑτέρας δυνάμεως αἰσθάνει, ἀδύνατον εἶναι δι ̓ ἄλλης ταῦτ ̓ αἰσθέσθαι, οἷον ἃ δι ̓ ἀκοῆς, δι ̓ ὄψεως, ἢ δι ̓ ὄψεως, δι ̓ ἀκοῆς ;

3 De An. 11. 6, 41820.

11. 7, 41925-30. III. 13, 435 15.