CLASSICAL ANTIQUITY, MIDDLE AGES 37 



natural that everything that happens has an intellectual cause, and every- 

 thing exists to serve a given purpose. This purpose is, above all, the develop- 

 ment of a higher form, the striving towards a higher intellectual existence. 

 Natural necessity and its cause, chance, have, it is true, their part to play on 

 the earth, but only as an attendant of incomplete matter; in the heavenly 

 spheres nothing happens by chance, but all is intellectual, while on the 

 earth the higher intelligence is victorious over its lower opponents. But con- 

 sequently terrestrial life, including man, is also governed by the higher 

 intelligence of the heavenly bodies, which get their impulses direct from 

 God. 



The first evolutionist 

 Thus Aristotle makes his biological theories a link in the general cosmogony 

 which he built up on the fundamental principle of the domination of form — 

 that is, of the spirit over matter, and of motion as the origin of all things. 

 The whole world of this thought-structure is as foreign to our modern ideas 

 as it could possibly be; Democritus' atomic theory is far nearer our own 

 notions. Nevertheless, Aristotle's theory implies an absolute advance in the 

 sphere of biology. Here we find enunciated for the first time a really complete 

 theory of evolution. To the old natural philosophers, Democritus among 

 them, existence was a casual change of different forms. Again, Aristotle saw 

 a consistent evolution from lower to higher forms of being, and although it 

 is based on purely metaphysical speculation, this idea has proved for all time 

 a fertile one in the biological sphere, for the very reason that it is here in 

 agreement with actual fact. Quite in accordance with this his fundamental 

 principle, Aristotle also made special investigation into the development of 

 animals from the tgg and embryo to the perfect state, and in this sphere he 

 has made his most important contribution to biological research. But other- 

 wise his philosophical and educational activities embraced the whole of 

 biology, as it was known at that time, as well as all natural phenomena in 

 general. Of his purely biological works the following are extant: ten books 

 On the History of Animals, of which, however, three are considered spurious; 

 four books On the Parts of Animals; five books On the Reproduction of Animals; 

 and three books On the Soul. In these treatises he has collected all contempo- 

 rary knowledge of animal life, not only his own and his pupils' personal 

 observations, but also all the knowledge that his extensive collections of 

 books could impart regarding the observations of the earlier philosophers. 

 All this material he worked up with a view to including it in his general 

 cosmic theory. It has been said that "never before or since has a scheme been 

 so completely carried out with a view to incorporating biology in one com- 

 mon science, while at the same time by personal observations and literary 

 notes systematically building it up into one unit out of the phenomena" 

 (Burckhardt). This is true, and the reason for it is to be found in that unique 



