THE EVOLUTION IDEA 137 



In the eiglitli rank of prerogative instances, we 

 will place deviating instances, such as the errors of 

 nature, or strange and monstrous objects, in which 

 nature deviates and turns from the ordinary course. 

 For the errors of nature differ from singular in- 

 stances, inasmuch as the latter are the miracles of 

 species, the former of individuals. Their use is much 

 the same, for they rectify the understanding in op- 

 position to habit, and reveal common forms. For 

 with regard to these, also, we must not desist from 

 inquiry, till we discern the cause of the deviation. The 

 cause does not, however, in such cases rise to a regu- 

 lar form, but only in the latent process toward such 

 a form. For he who is acquainted with the paths of 

 nature, will more readily observe her deviations ; and 

 vice versdy he who has learned her deviations will be 

 able more accurately to describe her paths. 



Having thus spoken of deviations or varia- 

 tions, and of the necessity of understanding the 

 normal type in order to detect the variation, also 

 of the desirability of studying the cause of the 

 variation, Bacon^ proceeds to assert that it is pos- 

 sible for man to produce variations experimen- 

 tally, and shows that living objects are well 

 adapted to experimental work: 



They differ again from singular instances, by be- 

 ing much more apt for practice and the operative 

 branch. For it would be very difficult to generate new 

 species, but less so to vary known species, and thus 



