4 THEORIES OF SPONTANEOUS GENERATION 



are in constant motion and are separated from one another 

 by empty spaces. This mechanical motion of the atoms is 

 inherent in matter, and on it depends the process of organisa- 

 tion of all individual objects. In particular, life appears, not 

 from an act of divine creation, but as the result of the 

 mechanical forces of nature itself. According to Democritus 

 the primary development of living creatures, or their spon- 

 taneous development from water and mud, occurs when 

 minute particles of moist earth come together with atoms 

 of fire in a fortuitous but completely determinate way in the 

 course of their mechanical movement. Another illustrious 

 ancient Greek thinker, Epicurus^ (342-271 B.C.) took up the 

 same philosophical position a hundred years later. We may 

 find an exposition of his views in the well-known poem of 

 Lucretius Carus, De rerum natural According to this source, 

 Epicurus taught that, thanks to the moist heat of the sun 

 and the rain, there arise from earth or manure, worms and 

 a multitude of other creatures. But this happens without 

 the participation of any spiritual influence whatever. Spirits, 

 in the form of non-material forces, do not exist, according 

 to Epicurus. The spirit is material and consists of small, very 

 delicate and smooth atoms. The mechanical juxtaposition of 

 atoms in empty space also leads to the formation of multi- 

 farious things, in particular, living beings. According to 

 him, the cause of the motion of the atoms resides in matter 

 itself and does not depend on any ' initial impulse ' or other 

 meddling of gods in the affairs of the world. 



Thus, even hundreds of years before the beginning of 

 our era, the phenomenon of spontaneous generation was 

 explained materialistically by many schools of philosophers 

 as being the self-creation of living things without the parti- 

 cipation of any spiritual forces. The matter may be summed 

 up historically by saying that the later development of the 

 idea of spontaneous generation was bound up, not with the 

 materialistic ' line ' of Democritus but with the opposing 

 idealistic ' line ' of Plato. 



Plato himself (427-347 b.c.) hardly concerned himself directly 

 with the problem of spontaneous generation. In the Phaedo 

 he only touches superficially on the question of the possibil- 

 ity of the formation of living things under the influence of 



