INTRODUCTION. 163 



length : l " That the generation of bees takes place in this way 

 appears both from reason and from those things that are seen 

 to occur in their kind. Still all the incidents have not yet 

 been sufficiently examined. And when the investigation shall 

 be complete, then will sense be rather to be trusted than rea- 

 son; reason, however, will also deserve credit, if the things 

 demonstrated accord with the things that are perceived by 



Of the Method to be pursued in studying Generation. 



Since in Animal Generation, (and, indeed, in all other sub- 

 jects upon which information is desired,) inquiry must be begun 

 from the causes, especially the material and efficient ones, it 

 appears advisable to me to look back from the perfect animal, 

 and to inquire by what process it has arisen and grown to ma- 

 turity, to retrace our steps, as it were, from the goal to the 

 starting place ; so that when at last we can retreat no further, 

 we shall feel assured that we have attained to the principles ; 

 at the same time we shall perceive from what primary matter, 

 and from what efficient principle, and in what way from these 

 the plastic force proceeds ; as also what processes nature brings 

 into play in the work. For primary and more remote matter, 

 by abstraction and negation (being stripped of its garments as 

 it were) becomes more conspicuous; and whatever is first formed 

 or exists primarily in generation, is the material cause of every- 

 thing that succeeds. For example, before a man attains to 

 maturity, he was a boy, an infant, an embryo. And then it is 

 indispensable to inquire further as to what he was in his mother's 

 womb before he was an embryo or foetus ; whether made up of 

 three bubbles, or a shapeless mass, or a conception or coagulum 

 proceeding from the mingled seminal fluids of his parents, or 



1 De Gen. An. lib. iii, c. 10. 



