ANCIENT AND MEDIAEVAL BELIEFS I5 



bodies of animals and men and which can be controlled by 

 means of magic remedies. This force itself determines the 

 formation of the organism and its later conduct. Paracelsus 

 developed a theory of spontaneous generation of life with 

 this philosophical outlook. He even produced a number of 

 personal observations of the sudden formation of mice, frogs, 

 eels and tortoises horn water, air, straw, rotten wood and all 

 sorts of rubbish." The descriptions of the views and beliefs 

 of the learned men of the Middle Ages were excellently 

 portrayed in Goethe's tragedy Faust. Here Mephistopheles 

 refers to himself as " Der Herr der Ratten und der Mduse, 

 der Fliegen, Frosche, Wanzen, Lduse " , and a swarm of insects 

 fly out fiom his old doctor's fur cloak and praise him not 

 only as their patron but also as their father, as though he had 

 actually begotten them there and then. 



The part played by the homunculus in the second part of 

 Faust is also well known. Wagner takes great pains with the 

 preparation of his alchemical experiments. For this he mixes 

 hundreds of substances, corks them up in a retort and 

 proceeds to purify them by distillation. If the conjunction 

 of the stars were favomable a manikin should develop in the 

 retort. But even in this case the spontaneous generation did 

 not occur without the intervention of Mephistopheles, whom 

 the homunculus greeted as his ' cousin ' }^ 



In the second half of the sixteenth century and, in par- 

 ticular, in the seventeenth century, observations of natural 

 phenomena were getting more accurate. Copernicus (1473- 

 1543), Bruno (1548-1600) and Galileo (1564-1642) destroyed 

 the old Ptolemaic system and drew up sound theories concern- 

 ing the universe of stars and planets which surround us.^^ 

 However, this blossoming of exact knowledge did not as yet 

 touch upon biological problems. The idea of the primary 

 spontaneous generation of living things remained unchal- 

 lenged in the minds of the investigators of that time. 



As an example we may here mention the well-known 

 physician of Brussels, van Helmont (1577-1644). He used 

 some methods of exact experiment which enabled him to 

 make substantial progress in the study of the complicated 

 problem of the nutrition of plants. Nevertheless, he was 

 quite convinced that living things could arise by spontaneous 



