l8 THE HISTORY OF BIOLOGY 



alternately to and from the skin, the air is inhaled in conjunction with it. 

 The perceptions of the senses are due to the objects that are perceived or 

 sensed giving off fine particles, which unite themselves to the corresponding 

 components in the organs of sense. Thus the various elements are apprehended 

 by corresponding elements in the organs of sense: water by water, air by air, 

 etc. Tones are created by the air brought into movement forcing its way into 

 the auditory duct of the ear as into a trumpet. Empedocles is said to have 

 been the first to describe the labyrinth of the ear. The eye he compares to a 

 lamp; light is distinguished by the eye's fire-components, darkness by its 

 water-particles. Even in the operation of thinking he sees a purely corporeal 

 function; the blood, in which all the elements are most minutely commingled, 

 is the seat of intelligence, but in this other parts of the body can also co- 

 operate; elsewhere in the operation of thinking the four elements in the 

 thinker and the thought seek one another. The more finely and evenly the 

 elements are mixed in a man, the better does he think; if the correct mixture 

 is confined to particular parts of the body, then these parts are more highly 

 developed than the others. — In curious contrast to this materialistic theory 

 of sensation are several utterances of Empedocles in which, like Parmenides, 

 he warns us that the evidence of the senses cannot be implicitly trusted; they 

 can deceive, while the reasoned thought is infallible. 



We cannot here enter into a discussion of Empedocles* religious theories. 

 Like Pythagoras, he believed in the migration of the soul and likewise for- 

 bade his disciples to kill and eat animals. Even certain plants were in this 

 respect sacred. For the rest, it is difficult to reconcile his mystical religious 

 pronouncements and his miracle-working activities with his natural philoso- 

 phy, which so strictly emphasized the doctrine of causality. From a closer 

 knowledge of the conditions under which he lived we might well have 

 been able to explain the riddle; now he stands as a unique, strange phenome- 

 non in the history of biological research. 



Empedocles' scientific influence 

 In this sphere he undoubtedly deserves a high place. In particular his specu- 

 lations on the constitution of matter and its changes are worthy of atten- 

 tion. While his predecessors and even his successors for long ages afterwards 

 had no other natural grounds of explanation to offer in regard to these 

 phenomena than motion in space, Empedocles comes forward with a kind 

 of doctrine of affinity, crude and clumsy, it is true, but nevertheless con- 

 taining within it the germ of a number of ideas which it was only possible 

 for far later ages to think out. And the fact that these ideas were not adopted 

 by his successors, that antiquity failed to produce any science of chemistry, 

 does not detract from their interest. His physiological speculations, naive 

 though they are, also give evidence of his keen powers of observation and 

 combination. In his curious theory of the creation of living organisms from 



