ANCIENT AND MEDIAEVAL BELIEFS 5 



warmth and decay. However, in complete harmony with his 

 general philosophical position, he maintained that life is not 

 inherent in plant and animal matter but this can only be 

 brought to life by the infusion into it of the immortal spirit 

 or Psyched 



This idea of Plato's played a tremendous part in the later 

 development of the problem in which we are interested. It 

 was reflected to some extent in the teaching of Aristotle 

 which later formed the basis of the mediaeval scientific 

 culture and dominated people's minds for nearly 2000 years. 



Aristotle (384-322 b.c.) gave to mankind by far the broadest 

 synthesis of the achievements of ancient science, embracing 

 all the factual material ^vhich had been accumulated up till 

 that time. He unfolded his views on the origin of life in 

 a number of biological works concerning the origin of 

 animals: Historia animalium, De partihus animaliiun , and 

 De generatione animalium}'^ According to Aristotle animals 

 are born from others like themselves but equally, they arise 

 and always have arisen by spontaneous generation from non- 

 living matter. He wrote as follows : 



Such are the facts, everything comes into being, not only from 

 the mating of animals but from the decay of earth and dung. . . . 

 And among plants the matter proceeds in the same way, some 

 develop from seed, others, as it were, by spontaneous generation 

 by natural forces ; they arise from decaying earth or from certain 

 parts of plants. 



Ordinary worms, the grubs of bees and wasps and also 

 ticks, greenflies and various other sorts of insects arise, 

 according to Aristotle, from dews in the presence of decaying 

 mud and dimg, from dry trees, hair, sweat and meat. All 

 sorts of intestinal worms are formed from decomposing parts 

 of the body and excreta. Midges, flies, moths, mayflies, dung 

 beetles, cantharides, fleas, bugs and lice (partly as such and 

 partly as grubs) arise from the slime of wells, rivers and seas, 

 from the soil of the fields, from mould and dung, from rot- 

 ting wood and fruit, the dirt of animals, from all sorts of 

 filth, from the sediment of vinegar and also from old wool." 

 Not only insects and worms but other living things can, 

 according to Aristotle, arise by spontaneous generation. Thus 



