object1: so that those in whom the light within the eye is defective should see worse by day. Or if (as Empedocles thinks) its like augments the visual fire in the daytime3, while its opposite destroys or thwarts it, then all should see white objects better by day, both those whose internal light is less and those whose internal light is greater; while again all should see black objects better by night. The fact is, however, that all animals except a very few see all objects better by day than in the night-time. It is natural to suppose that in these few their native fire has this peculiar power, just as there are animals whose eyes in virtue of their colour are luminous at night. Again, as regards the eyes in which the fire and water are mixed in equal proportions, it must follow that either is in turn unduly augmented by day or by night: hence, if water or fire thwarts vision by being in excess, the disposition (diábeσis) of all eyes would be pretty nearly alike 5.’ Democritus. Democri § 12. For Democritus, as for Empedocles, the most General obvious explanation of perception seemed to be that which view of the physical showed how particles of external things come into the theory of pores of the sensory organs. He differed from Empedocles tus in its in his doctrine of the existence of void, which Empedocles bearing on did not allow. They agreed, however, in the belief that function : 1 This is perhaps though see nute 4 infra-an arg. ad hominem against Empedocles: Theophrastus, as a disciple of Aristotle, would not hold that the eyes contain a 'small fire,' to be quenched by the greater fire of the sun. 2 Instead of better, as Empedocles asserts 3 i. e. if (instead of the greater fire without destroying the less within the eye) the daylight augments the intra-ocular fire. * Not 'cutis noctu magis splendet,' as in Wimmer's Latin version. There would seem to be here on the critic's part an admission which is contrary to the teaching of Aristotle. Theophrastus seems to attribute the capacity of some animals to see by night to the possession of a peculiar fire in their eyes. 5 i. e. the so-called best class of eyes, having water and fire in equal proportions, would both by day and by night, in one or the other way, be out of keeping with the conditions of perfect vision, and would therefore not have the superiority claimed for them by Empedocles : they would be no better than the eyes already referred to. visual tion and of the eye as organ of vision in and medium. Vision by means of pupillar image. the nature like is perceived by like1. Instead of holding, like Empedocles, that there are four elements qualitatively distinct, generally, Democritus with Leucippus (of whom so little is known separately that we can neglect him or merge him in his pupil) taught that the elements of things are homogeneous relation to atoms, infinitely numerous, moving eternally in void. The the object introduction of atoms in certain ways through the organs 'to the soul' was for him (as the introduction of ảπoppoal was for Empedocles also) the essence of perception. We perceive an external thing by its being thus introduced into the soul; but the soul, for him as for Empedocles, is itself material, so as to be capable of being affected in the way perception implies. It consists of atoms of a certain shape endowed with a certain order and movement. The impression made by the atoms of the object on the soul must be of a certain initial strength, in order to be noticeable. For Democritus (as for Empedocles2, to some extent) the organs are thus essentially passages-thoroughfares for instreaming atoms. All the senses are modes of one, viz. Touching 3. The essential feature of the eye is, for Democritus, its moist and porous nature, while the ear is a mere channel for the conveyance of sonant particles inwards 'to the soul.' To reach the soul, the particles conveyed inwards require to be disseminated through the body. It is impossible for us, he thought, to receive wholly exact impressions of external things through the organs of sense. For example, in seeing, 1 As against the doubt of Theophr. de Sens. § 49 see Arist. 405 12-16; Sext. Emp. adv. Math. vii. § 116; Mullach, Democr., pp. 206, 401, and Theophr. himself § 50. Indeed, Democritus also held that 'like is affected by like'—a physical principle-while according to Aristotle (323b 3 seqq.) most philosophers with one accord assert that like cannot be affected by like (τὸ ὅμοιον ὑπὸ τοῦ ὁμοίου πᾶν ἀπαθές ἐστι). It is hard to see how the acceptance of the latter physical principle could be, as Mr. Archer-Hind (Plato, Tim., p. 205) says, compatible with that of the psychological axiom 'like is known by like.' 2 In his account of the formation of the ear, which he compares to a kódwv, Empedocles seems to have regarded this sense-organ, at least, as something more than a mere passage, and as having a determining power over the quality of the sensation to be produced by the ȧróppoiai. 3 Cf. Arist. 4428 29 Δημόκριτος καὶ . . . ἀτοπώτατόν τι ποιοῦσι· πάντα γὰρ τὰ αἰσθητὰ ἑπτὰ ποιοῦσι. the air intervening between us and the object interferes with our obtaining a correct impression or image of this, as is evidenced by the blurred look of distant things. Democritus first laid down the distinction of the qualities of body1 into the so-called primary and secondary qualities, to which, however, he did not himself remain always consistent. As Theophrastus (de Sens. § 80; see p. 35 infra) points out, we cannot quite follow his doctrine of the formation of colours unless we assume a púσis xpúμaros—an objective existence of colour. He held that vision is the result of the image of the object mirrored in the eye. But when we ask—what exactly is mirrored? the answer for him is not easy; since between object and eye come what he called deĺkeλa (generally spoken of by Aristotle and Theophrastus as elowλa), things which in the case of this sense are also referred to as απόρροιαι τῆς μορφῆς. These δείκελα, not the object, are therefore the immediate and proper data of sense. ' of Demo visual § 13. Democritus regarded the pupillar image as the Aristotle's essential factor of vision. 'Democritus,' says Aristotle 2, criticism 'is right in his opinion that the organ of vision proper critus' consists of water, but not when he goes on to explain theory. vision as the mirroring (čμþaσw) of objects in this For this mirroring is due to the fact that the of the eye is smooth, and the image exists really the mirroring eye but in the eye that beholds inasmuch as the case is merely one of reflexion *. But on misunder water. The latter surface stood the not in function of this3, in the eye. 1 The non-objectivity of colour is stated as a doctrine of his by Arist. 316* 1 Δημόκριτος . . . χροιὰν οὔ φησιν εἶναι, τροπῇ γὰρ χρωματίζεσθαι. Cf. Theophr. de Sens. § 64; also Galen. de Elem. sec. Hipp. i. 2 vóμw γὰρ χροιὴ . . . ἐτεῇ δ ̓ ἄτομον καὶ κενὸν ὁ Δημόκριτός φησιν. He is alluded to by Arist. 426 20 οἱ πρότεροι φυσιολόγοι οὐδὲν ᾤοντο οὔτε λευκὸν οὔτε μέλαν εἶναι ἄνευ ὄψεως κτέ. 2 Arist. 438 5-16. * The subject of ἔστιν is ἡ ἔμφασις derived from τοῦτο, sc. τὸ ἐμφαίνεσθαι ἐκείνῳ = τῷ ἐκεῖ ὁρωμένῳ. Here Aristotle's argument does not require the seeming admission of the Platonic view, viz. that vision is effected by an ovis, or ray, which goes forth from the beholder's eye and returns to this from the object. This view, rejected by him 435a 5, and de Sens. ii, is one which Aristotle himself, provisionally at least, adopts Meteor. iii. 2. 373b seqq.; vide Ideler, Meteor. ii. pp. 273 seqq.; Galen. de Placit. Hipp. et Plat. § 640. 4 Εμφασις in the eye, like all other ἔμφασις, is to be explained by the water of Demo critus' theory: the object of vision the air, and the whole it would seem that in his day no scientific knowledge yet existed of the way in which images are formed in mirrors, or of the reflexion of light in general. It is strange, too, that Democritus should never have asked himself why, if his theory of vision be true, the eye alone sees, while none of the other things, in which images are also Peculiarity mirrored, do so.' 'Democritus holds1 that we see by the reflexion of images, but describes this latter process in a way peculiar to himself. It does not, he says, take place directly in the pupil from the object; but the air between impresses object and eye is impressed with a sort of stamp while> this im- being dispatched in a compact form from the object to pressed air is what the organ; for emanation is always taking place from everything. This air, then, being solid, and of different colour, reflects itself in the eyes, which are moist. A dense body does not admit (this air-impression), but one that is moist, like the eye, gives it free passage. Hence moist eyes see better than those that are (dry and) hard, provided that their outer membrane is as thin and dense as possible, and that the inner parts are spongy and free from dense and solid tissue, as well as from such moisture as is thick and glutinous; and that the veins of (or, connected with) the eyes are straight and free from moisture, so as to conform in shape to the images moulded by, and thrown off from, the object 5.' affects the eye. This intermediate effect of the object in moulding the ávákλaois, i. e. the bending back of the oys from the reflecting surface. The image, supposed to be in the mirror, is a set of rays reflected to this from the object, and from it to the beholder's eye, in which therefore it really is. Thus the image 'seen in the eye' of A cannot explain how A sees. Cf. R. Bacon, O. M. Persp. III, Dis. i. cap. 2, ' nihil est in speculo . . . ut vulgus aestimat." 1 Theophr. de Sens. § 50 (Diels, Dox., p. 513 n.). 2 The reading suggested by Diels κατὰ—for καὶτοῦ ὁρῶντος has been translated, but συστελλόμενον has been preferred to his στελλό μevov: the preposition is defended by the words of Theophrastus, § 52 ὠθούμενος καὶ πυκνούμενος. From the eye: see infra Anaxag. § 20, Diogenes of A. § 23. • Adopting Usener's στιφρᾶς for ἰσχυρᾶς. 5 ὡς (= ώστε) όμοιοσχημονεῖν τοῖς ἀποτυπουμένοις. air into definite visible forms (ànотúпwσis) is the peculiar characteristic of Democritus' theory of vision. He held that if there were pure vacuum, and not air, around us, the emanations or images sent from the visible objects would reach the eye unblurred: that is to say, they would then report the exact form of an object, no matter how great the distance from which they might come. 'Democritus,' says Aristotle', 'is not correct in his view that, if the space between object and eye were pure void, an ant could be seen clearly in the sky.' As it is, however, the air takes the first copy of the object, and the eye receives it only at second hand, while the likeness of this copy to the original becomes more and more imperfect in proportion to the distance it has to travel. criticizes critus' theory of vision. § 14. Theophrastus2 criticizes these tenets of Demo- Theocritus: His notion of modelling (anотúnwσis) in air is phrastus quite absurd. Whatever is capable of being moulded into Demoshape must have density, and must not be liable to dispersion; this he implies when he illustrates the process, and compares it with the stamping of impressions on wax. In the next place, such modelling might take place more successfully in water than in air, water being more dense; hence we should see better in water. As a fact, however, we see worse. In the third place, why should one who (as Democritus in his treatise Teрl eldôv ́does) believes in the emanation of the shape of an object3, hold this further belief in the modelling of the air? For the actual images (eïdwλa avrá) of the objects are represented in the eye, according to the former belief. But, again, if we grant that, as Democritus says, the air is moulded into shape, being like wax impressed and condensed, how does the reflexion of an image take place, and of what nature is it? If there is really such an image, i.e. an impression taken by the air from the object seen, it must be, in this as in other instances, on the side facing the latter. Such being the case, the image cannot come opposite to the eye unless the moulded portion of air is first De Sens. §§ 51 seqq. (Diels, Dox., pp. 513-15). 1 419a 15. 3 ἡ ἀπορροὴ τῆς μορφῆς. |