24 PIONEERS OF EVOLUTION PART 



same images provoke our minds which provoke them 

 when we are awake, and to such a degree that we 

 seem without a doubt to perceive him whom life has 

 left, and death and earth gotten hold of. This nature 

 constrains to come to pass because all the senses of 

 the body are then hampered and at rest throughout 

 the limbs, and cannot refute the unreal by real things ' 

 (cf. Bk. i. 134, 135 ; iv. 462-468; v. 1169-1176). 



In the fifth book Lucretius deals with origins 

 of the sun, the moon, the earth (which he held to 

 be flat, denying the existence of the Antipodes) ; of 

 life and its development ; and of civilisation. In 

 all this he excludes design, explaining everything as 

 produced and maintained by natural agents, ' the 

 masses, suddenly brought together, became the rudi- 

 ments of earth, sea, and heaven, and the race of 

 living things.' He believed in the successive appear- 

 ance of plants and animals, but in their arising 

 separately and directly out of the earth, * under the 

 influence of rain and the heat of the sun/ thus re- 

 peating the old speculations of the emergence of life 

 from slime, ' wherefore the earth with good title has 

 gotten and keeps the name of mother/ He did 

 not adopt Empedocles' theory of the ' four roots of 

 all things/ and he will have none of the monsters 

 the hippogriffs, chimeras, and centaurs which 

 form a part of the scheme of that philosopher. 

 These, he says, ' have never existed/ thus showing 

 himself far in advance of ages when unicorns, 

 dragons, and suchlike fabled beasts were believed 

 to exist. In one respect, more discerning than 

 Aristotle, he accepts the doctrine of the survival 

 of the fittest as taught by the sage of Agrigentum. 



