Volume 5

Treasury of human inheritance / edited by Karl Pearson, R.A. Fisher, L.S. Penrose.

Date:
1909-
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Treasury of human inheritance / edited by Karl Pearson, R.A. Fisher, L.S. Penrose. Source: Wellcome Collection.

    11/190 (page 127)
    fire and less water than others, some less fire and more water, some again have the fire in the centre and others at a point outside this, which affords the reason why some animals see more keenly in the daytime, others by night 1 .” Democritus again makes a very astute observation; he discusses in some detail the characters of objects which are associated with different colours and asserts that colour has no objective existence but that the colours of bodies are due to the position of the atoms in them 3 . We should scarcely expect a metaphysician to contribute greatly to the knowledge of his day on a subject requiring for its elucidation a close observation of facts as the basis of reasoning, but it cannot fail to be of interest to consider the contribution of so great a genius as Plato to the theory of colours and colour vision. An examination of Beare’s work and of Jowett’s translation of Plato’s Dialogues leads one to the conclusion that Plato contributed nothing to the existing knowledge on the subject, but we would urge that the following passage, taken from Beare, is approaching the recognition of some relation between light and colour. “For the power of seeing may be in the eye, and the man who possesses it may strive to exercise it; also colour may be present in the object, but if a third thing called light be not present the eye can see nothing, the colour must remain invisible” 3 —even though Plato possibly refers to light merely as opposed to darkness and obviously failed to realise that colour was an attribute belonging to light rather than to the object. Further, we owe to Plato in the Theaetetus our knowledge of the Heraclitean theory of colours 4 . Theaetetus asks, “Then what is colour?” Socrates replies: “Let us carry out the principle which has just been affirmed that nothing is self-existent and then we shall see that every colour, white, black, and every other colour, arises out of the eye meeting the appro priate motion and that what we term the substance of each colour is neither the active nor the passive element but something which passes between them and is peculiar to each percipient; are you certain that the several colours appear to every animal—say, to a dog—as they appear to you?” “Indeed I am not,” replies Theaetetus 5 . Again, “When the eye and the appropriate object meet together and give birth to whiteness and the sensation of white which could not have been given by either of them going to any other object, then, while the sight is flowing from the eye and whiteness from the colour-producing element, the eye becomes fulfilled with sight, and sees and becomes not sight but a seeing eye; the object which combines in forming the colour is fulfilled with whiteness and becomes not whiteness but white, whether wood or stone or whatever the object may be which happens to be coloured white 0 .” In the same dialogue we find: “But now, since not even white continues to flow white and the very whiteness is a flux or change which is passing into another colour and will not remain white, can the name of any colour be rightly applied to anything 7 ?” It would seem then that we at any rate owe to Plato the first suggestion, taken possibly from Heraclitus, that individual colours do not necessarily appear the same to all people. May we take this as an indication of the recognition of colour-blindness in his day? 8 And further, Plato seems to have first raised the question of the existence and character 1 Bibl. No. 299, p. 20. 2 Bibl. No. 299, p. 37. 3 Bibl. No. 299, p. 48. 4 The writer has been unable to find any account of the Heraclitean theory of colours elsewhere. 6 Bibl. No. 1, Yol. hi, p. 375. 0 Bibl. No. 1, Vol. in, p. 378. See also Greenwood (Bibl. No. 341), to whose work we are here indebted for references. 7 Bibl. No. 1, Vol. in, p. 407. 8 We fear not, but we feel that the statement might well have led Plato’s followers to a recognition of the facts. 17—2