40 THE RIDDLE OF THE UNIVERSE. 



there were certain peculiar changes, especially move- 

 ments, which were wanting in lifeless nature : spon- 

 taneous locomotion, the beat of the heart, the drawing 

 of the breath, speech, and so forth. But the discrimi- 

 nation of such "organic movements" from similar 

 phenomena in inorganic bodies was by no means 

 easy, and was frequently impossible ; the flowing 

 stream, the flickering name, the rushing wind, the 

 falling rock, seemed to man to exhibit the same move- 

 ments. It was quite natural that primitive man 

 should attribute an independent life to these " dead " 

 bodies. He knew no more of the real sources of 

 movement in the one case than in the other. 



We find the earliest scientific observations on the 

 nature of man's vital functions (as well as on his 

 structure) in the Greek natural philosophers and 

 physicians in the sixth and fifth centuries before 

 Christ. The best collection of the physiological facts 

 which were known at that time is to be found in the 

 Natural History of Aristotle ; a great number of his 

 assertions were probably taken from Democritus and 

 Hippocrates. The school of the latter had already 

 made attempts to explain the mystery ; it postulated 

 as the ultimate source of life in man and the beasts 

 a volatile " spirit of life " (Pneuma) ; and Erasistratus 

 (280 b.c.) already drew a distinction between the 

 lower and the higher " spirit of life," the pneuma 

 zoticon in the heart and the pneuma psychicon in the 

 brain. 



The credit of gathering these scattered truths into 

 unity, and of making the first attempt at a systematic 

 physiology, belongs to the great Greek physician, 

 Galen ; we have already recognised in him the first 

 great anatomist of antiquity (cf. p. 23). In his 



