HISTOKY OF EVOLUTION PETRONIEVICS. 327 



and the Orphics. But Thales is the first who clearly conceives the 

 natural origin of the world when he teaches the existence of a 

 primordial material from which everything is derived. His disciple, 

 Anaximander, goes much further ; he is the first declared exponent of 

 the evolutionistic idea; he teaches the gradual development of the 

 world from an unknown material, and a regular succession of periods 

 of the evolution and dissolution of the universe. He also teaches the 

 evolution of the earth, and he supposes a spontaneous generation of 

 organisms in the water (men, themselves, first appeared in the form 

 of fishes). Anaximenes and Diogenes of Appolonia also admit the 

 successive periods of the evolution and dissolution of the universe; 

 while the doctrine of Pythagoras and the Pythagoreans, although 

 insufficiently known, seems to be that of the eternality of the world. 

 Heraclitus adds to the idea of successive periods of evolution and dis- 

 solution of the universe, his doctrine of perpetual change. But it is in 

 the doctrine of Empedocles that the evolutionistic idea reaches its 

 height among the pre-Socratic philosophers. Being himself a sup- 

 porter of the idea of successive periods of evolution and dissolution 

 of the universe, he also conceives this world evolution process as going 

 on in a mechanically causal way and he explains this as the inter- 

 action of the four elements and the two forces which unite and 

 separate them. According to his belief, also, organisms arise from a 

 process of spontaneous generation, but he held that it is never com- 

 plete organisms which are formed, but only parts of organisms, called 

 organs. When they unite, these parts at first form organic combi- 

 nations incapable of living and propagating themselves, and it is 

 only after a series of successive creations of this kind that organisms 

 finally appear which are capable of self subsistence. The founders 

 of atomism, Leucippas and Democrites, took over the essential 

 features of Empedocles' doctrine, and perfected the mechanical side 

 of it by their doctrine of atoms. 



Finally, Anaxagoras, the last of the pre-Socratic philosophers, is 

 the only one of these, who, while admitting an infinite number of ele- 

 ments all different in quality, also supposes chaos as the initial state 

 of the world, and that this world developed itself out of chaos when it 

 received from God the first impulsion. Anaxagoras is also the first 

 who teaches the peculiar doctrine of the eternality of organic germs. 



The teachings of Plato concerning the world and organic species, 

 which he conceives clearly for the first time by means of his doctrine 

 of ideas, is very little understood on account of the allegorical form 

 which Plato generally gave to all his doctrines, and especially to his 

 theory of the creation of the world in his " Timeon." But it seems to 

 me that the true Platonic doctrine is a system of emanation, in which 

 God and pure nothingness (identical with empty space and matter) 

 are the two opposite poles. 



