ZOOLOGY EMERGES 47 



A barren period of intellectual life followed. Al- 

 though the intellectual life of the middle ages was 

 active among theologians, philosophers and other 

 educated classes it was so directed that for a period 

 of a thousand years, under the dominance of theolog- 

 ical authority, no really productive writings resulted. 

 The leading medical men kept alive some spirit of 

 investigation but it was confined to their own craft 

 and was handed along by preceptor to pupil without 

 becoming common property. Their occupation 

 brought them into touch with natural phenomena. 

 They knew the properties of herbs and their effects 

 on the human body. They became acquainted to 

 a limited degree, with anatomy and physiology. 

 Finally, it was through the medical men that renewal 

 of observation on organic nature was brought about. 



Renewal of Observation. Nearly nineteen cen- 

 turies after Aristotle there occurred, as one of the 

 features of the Renaissance, a revival of the scientific 

 method bringing once more into human affairs the 

 indispensable conditions even for the existence of 

 science. As the decline of science had been largely 

 due to the arrest of inquiry, and the substitution of 

 authority for investigation as the method of ascer- 

 taining truth, so the renewal, so far as progress of 



