yo THE HISTORY OF BIOLOGY 



ments, and pure poison. Such magic brews were prepared among the nations 

 of antiquity by witches and wizards and are still concocted amongst inferior 

 peoples and even amongst more primitive strata of higher types to this very 

 day. That the enlightened scientists of antiquity refused to associate them- 

 selves with such magical preparations was but natural; it required that 

 tendency towards the vulgar and the fantastic which the decline of ancient 

 culture evoked in the scientific world, before the methods of popular sorcery 

 could begin to be of interest to thinking and inquiring minds as well. Nor 

 indeed does the earliest experimental science deny this origin; it appears in 

 the form of alchemy, with its pronounced mystical aims, and above all in 

 the conversion of base metals into precious metals, the discovery of elixirs 

 of life and immortality, the reproduction of homuncules, etc. — aims to 

 which it adhered throughout the Middle Ages, even after its means and 

 methods had become characterized, at least in certain features, by a fair 

 measure of exactness and an extensive knowledge of the inorganic objects of 

 nature in particular. It was therefore at a later stage than any other branch 

 of exact science that the experimental branch succeeded in freeing itself from 

 its connexion with the supernatural world of thought, from which all science 

 gradually broke away. It is only the research work of more modern times 

 that has been able to enjoy to the full the advantages which experimental 

 science offers. 



Arabian natural philosophers 

 With biology the famous Arabian alchemists, one Geber and others, had 

 nothing to do; they occupied themselves only with inorganic nature. On 

 the other hand, the East possessed a number of purely speculative re- 

 searchers who dealt with the phenomena in living nature from a theo- 

 retical point of view and who exercised a lasting influence on the conception 

 of them in succeeding ages. All these philosophers took Aristotle as the 

 starting-point for their researches and, as already mentioned, they likewise 

 gave to their own often quite daring speculations the form of commentaries 

 on his works. Indeed, their position was always fraught with danger; they 

 were looked upon with suspicion by the orthodox Mohammedans, who be- 

 lieved that all studies that did not concern the Holy Koran were prohibited. 

 Against these constant persecutions they had no other support than the pat- 

 ronage of some science-loving prince, which had to be won and sustained by 

 flattery and was at best an unreliable guarantee of life and maintenance. 

 These philosophers held no posts as teachers — in the Mohammedan East 

 there were colleges only for students of the Koran — but their scientific 

 researches were always a private occupation; by profession they were fre- 

 quently physicians, sometimes lawyers, officials, or courtiers. 



Among these oriental thinkers there are primarily two who exerted 

 some influence on the progress of science even in the West, their writings 



