486 NATURAL HISTORY. 



produced by a weak and casual heat; nor out 

 of matter which is not exactly prepared according 

 to the species. The second is, for that there is 

 a greater time required for maturation of perfect 

 creatures ; for if the time required in vivification 

 be of any length, then the spirit will exhale before 

 the creature be mature ; except it be inclosed in 

 a place where it may have continuance of the heat, 

 access of some nourishment to maintain it, and close 

 ness that may keep it from exhaling : and such 

 places are the wombs and matrices of the females. 

 And therefore all creatures made of putrefaction 

 are of more uncertain shape ; and are made in 

 shorter time ; and need not so perfect an inclosure, 

 though some closeness be commonly required. As 

 for the Heathen opinion, which was, that upon 

 great mutations of the world, perfect creatures 

 were first engendered of concretion ; as well as frogs, 

 and worms, and flies, and such like, are now ; 

 we know it to be vain: but if any such thing 

 should be admitted, discoursing according to sense, 

 it cannot be, except you admit a chaos first, and 

 commixture of heaven and earth. For the frame 

 of the world, once in order, cannot affect it by any 

 excess or casualty. 



