24 GENERATION OF INSECTS 



Earth, and finally by those which are about to decay and 

 return to dust. Hence others have claimed putrefaction 

 itself to be the all-potent cause of generation, and still 

 others, natural heat. Many additional causes have been 

 adduced, conforming to the divers modes of thought of 

 different sects, who speak of active and efficient forces, 

 the world soul, so to say — the spirit of the elements, 

 ideas, the heavens, their light and motion, and higher in- 

 fluences. Nor was there lacking the assertion that the 

 generation of all insects is caused by the generative prin- 

 ciple residing in the original and sentient vegetative 

 souls, of which particles remain alive in the dead bodies 

 of animals and plants, in a quiescent state, which is 

 changed into activity by contact with surrounding heat 

 and communicates new life to corrupt matter. There is 

 still another class of wise persons who hold it to be true 

 that generation proceeds from certain minute agglomera- 

 tions of atoms, which contain the seed of all things. 

 These persons say further that the seed was created by 

 God at the beginning of the world and scattered in all 

 directions for the fertilization of the elements, bestowing 

 upon them, not a transitory, but a permanent fecundity 

 as stable as the elements themselves; in this way, they 

 say, are to be interpreted the words of the Sacred Book, 

 " God created all things together." But that great philos- 

 opher of our time, the immortal William Harvey, also 

 held that all living things are born from seed as from 

 an egg, be it the seed of animals of the same species or 

 elsewhere derived ; thus he says, " Because this is com- 

 mon to all living creatures, viz: that they derive their 

 origin either from semen or eggs, whether this semen 

 have proceeded from others of the same kind, or have 

 come by chance or something else. For what sometimes 



