And it is the same with hearing. Large animals can hear great and distant sounds, while less sounds pass unperceived; small animals perceive small sounds and those near at hand.[[729]] It is the same too with smell. Rarefied air has more smell; for, when air is heated and rarefied, it smells. A large animal when it breathes draws in the condensed air along with the rarefied, while a small one draws in the rarefied by itself; so the large one perceives more. For smell is better perceived when it is near than when it is far by reason of its being more condensed, while when dispersed it is weak. But, roughly speaking, large animals do not perceive a rarefied smell, nor small animals a condensed one.[[730]]
This theory marks in some respects an advance upon that of Empedokles. It was a happy thought of Anaxagoras to make sensation depend upon irritation by opposites, and to connect it with pain. Many modern theories are based upon a similar idea.
That Anaxagoras regarded the senses as incapable of reaching the truth of things is shown by the fragments preserved by Sextus. But we must not, for all that, turn him into a sceptic. The saying preserved by Aristotle[[731]] that “things are as we suppose them to be,” has no value at all as evidence. It comes from some collection of apophthegms, not from the treatise of Anaxagoras himself; and it had, as likely as not, a moral application. He did say (fr. [21]) that “the weakness of our senses prevents our discerning the truth,” but this meant simply that we do not see the “portions” of everything which are in everything; for instance, the portions of black which are in the white. Our senses simply show us the portions that prevail. He also said that the things which are seen give us the power of seeing the invisible, which is the very opposite of scepticism (fr. [21a]).
[647]. Diog. ii. 7 (R. P. 148), with the perfectly certain emendation referred to ib. 148 c. The Athens of 480 B.C. would hardly be a suitable place to “begin philosophising”! For the variation in the archon’s name, see Jacoby, p. 244, n. 1.
[648]. We must read ὀγδοηκοστῆς with Meursius to make the figures come right.
[649]. On the statements of Apollodoros, see Jacoby, pp. 244 sqq.
[650]. Diog., loc. cit. In any case, it is not a mere calculation of Apollodoros’s; for he would certainly have made Anaxagoras forty years old at the date of his arrival in Athens, and this would give at most twenty-eight years for his residence there. The trial cannot have been later than 432 B.C., and may have been earlier.
[651]. Arist. Met. Α, 3. 984 a 11 (R. P. 150 a).
[652]. Phys. Op. fr. 3 (Dox. p. 477), ap. Simpl. Phys. p. 25, 19 (R. P. 162 e).