328 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



Aristotle's system is the type of an antievolutionistic one. The inor- 

 ganic world is eternal, eternally expressing the corresponding thought 

 of the Divine Being. Although the founder of biology taught that all 

 organized beings form a continuous ladder of degrees of perfection 

 (from the most primitive plants to man, the most perfect animal) he 

 conceives this ladder in a purely static manner, since the organized 

 species were, to him, eternal and unchanging. But, on the other side, 

 he admits spontaneous generation, even for organized beings rela- 

 tively complex. A similar gradation in the domain of the mind is 

 taught by Aristotle. 



In post-Aristotelian philosophy Epicurus and his disciple, the 

 Roman poet Lucretius, especially merit our attention. In teaching the 

 infinity of space and of the number of atoms, Epicurus and Lucretius 

 expressly announce that the evolutionary process of worlds has a 

 definite beginning in time. According to them, there does not exist an 

 evolutionary process of the entire universe, but only evolutionary 

 processes in special worlds, separated in the great infinity of space. 

 They conceive these evolutionary processes as taking place in a purely 

 mechanical way, and they try to give, for the first time, a rational 

 explanation of the evolutionary processes of the worlds. They also 

 teach the evolution of the earth. Furthermore, in taking up Em- 

 pedocles' evolutionary doctrine with regard to the organic world, 

 Lucretius improves considerably upon this theory by teaching the 

 spontaneous generation of entire organisms which appear in a series 

 of beings more and more perfect. But that which most arouses our 

 admiration for the Roman poet and makes the reading of the fifth 

 book of his poem so extremely interesting is his theory of the evolu- 

 tion of the human race, of the human mind, of human society. We 

 feel that we are here almost in the presence of a modern scientist. 



Compared with Epicurus and Lucretius, the Stoics are almost re- 

 actionaries. They admit, according to Heraclitus, a periodic suc- 

 cession of universes, and they teach — this is their original theory — 

 the eternality of the germs of things which develop in each universe. 



The doctrine of the Neo-Platonists, Plotinus and Proclus, is the 

 theory of the eternality of the world, which came forth by a process 

 of emanation out of the supreme being, the pure oneness. 



In the middle ages, we find in St. Augustine an allegorical inter- 

 preter of the origin of things; St. Augustine supposes that inor- 

 ganic matter was created by God and given the power of self- 

 development through its own efforts to an ordered inorganic world. 

 He teaches in addition the eternality of the organic germs created by 

 God. St. Thomas Aquinas accepts the doctrine of St. Augustine, 

 although in a manner somewhat disguised. 



Among the Arabian philosophers, Avicennus is devoted to the 

 Neo-Platonic doctrine of emanation; he especially teaches, however, 



