CLASSICAL ANTIQUITY, MIDDLE AGES 19 



scattered parts brought together by chance an attempt has been made to see 

 a kind of primitive theory of selection. That is, of course, an exaggeration; 

 his anthropogeny gives even clearer evidence than Anaximander's of being 

 derived from the old legends of autochthones. 



With Empedocles the western Greek school made their final and most 

 important contribution towards the history of biology. A couple of hundred 

 years later this people saw the birth of their greatest philosophical genius, 

 the physicist Archimedes, who lived to see the destruction of the liberty of 

 western Greece. He was indeed a specialist in his own sphere, which has no 

 place in this work. We return therefore to Asia Minor, whence sprang the 

 whole of Greek natural philosophy and where the Ionian succession was still 

 being carried on with achievements of great importance for its further 

 development. 



From its point of departure in the Ionian philosophy Heracleitus of 

 Ephesus (about 510-450) developed an entirely new idea of nature. He was 

 one of the greatest philosophers of antiquity, called "the dark," on account 

 of both his obscure style of writing and his gloomy view of life. He came from 

 a distinguished priestly family, but resigned an eminent government post to 

 devote himself entirely to philosophy. His life, too, however, was disturbed 

 by political revolutions. As a thinker he seems to have been essentially auto- 

 didactic, and though his system is to a certain extent based on the Ionian 

 philosophy, mainly on that of Anaximander, it nevertheless bears an en- 

 tirely original stamp. In contrast to the Eleatics' assertion of the immuta- 

 bility of the universe, Heracleitus sums up his teaching in the proposition 

 that everything is mutable, that mutability is the essence of existence. 

 "Struggle is life" is a saying that comes from him; "All is flux" is another. 

 He regards fire as the causal principle of the cosmos. Everything has arisen 

 from a primordial fire, to which everything returns, for worlds arise and 

 perish alternately. Heracleitus saw divinity in the primordial fire. Fire is also 

 the soul of man; fire is inhaled in breathing, and its cessation is therefore 

 identical with death. Disease arises mostly through water, the enemy of fire, 

 predominating in the body; intemperance in drinking clouds the soul, since 

 the wine makes the soul humid; "The driest soul is the wisest," he expressly 

 states in his writings. His special biological investigations have not been 

 preserved. He is said to have dissected animals, but it is not known whether 

 he drew any fresh conclusions therefrom. The service he rendered to science 

 lies in his general view of existence; in his constant insistence on the modifi- 

 cation of the principle, and at the same time on incontrovertible natural law 

 governing the universe — these two factors being the essence of existence. 

 In this he exerted great influence upon the natural philosophy of succeeding 

 ages, particularly upon Plato and, through him, upon Aristotle. 



Contemporaneous with Heracleitus, however, there appears another 



