SPONTANEOUS GENERATION 153 



belief that so far all attempts to prove it have 

 failed utterly. 



St. Thomas Aquinas had a celebrated and some- 

 times misunderstood controversy with Avicenna, 

 a very famous Arabian philosopher. It was a 

 philosophical, but not strictly scientific, contro- 

 versy, for both persons accepted or assumed the 

 existence of spontaneous generation. Avicenna 

 claimed that it took place by the powers of 

 Nature alone, whilst St. Thomas adopted the 

 attitude which we should adopt to-day, were 

 spontaneous generation shown to be a fact, 

 namely, that if Nature possessed this power, it was 

 because the Creator had willed it so. 



We come to close quarters with the question 

 itself in 1668, when Franceso Redi (1626-1697) 

 published his book on the generation of insects 

 and showed that meat protected from flies by 

 wire gauze or parchment did not develop maggots, 

 whilst meat left unprotected did. From this 

 and from other experiments he was led to for- 

 mulate the theory that in all cases of apparent 

 production of life from dead matter the real ex- 

 planation was that living germs from outside had 

 been introduced into it. For a long time this 

 view held the field. Redi was, as his name in- 

 dicates, an Italian, an inhabitant of Aretino, a 

 poet as well as a physician and scientific worker. 

 He was physician to two of the Grand Dukes of 

 Tuscany and an academician of the celebrated 

 Accademia della Crusca. Those works which I 

 have been able to consult on the subject say 

 nothing about his religion, but there can scarcely 



