ESTIMATE OF LEIBNIZ S PHILOSOPHY 157 



entirely external to the events or things, but appearing in 

 them. But the meaning, the spirit of Aristotle's method 

 was lost sight of. 'Find a principle, a form, of any kind,' 

 came to be the rule of explanation. And thus the number 

 of 'substantial forms' or principles of substance was 

 multiplied indefinitely, while, in addition, the most 

 minute changes in substances were each explained by 

 reference to some ' accidental form ' or principle of 

 accident. Anything sufficed as an explanation so long 

 as it was called a form. Thus when no intelligible 

 account of a phenomenon could readily be given it was 

 attributed to some hidden principle (qualitas occulta), 

 which was described by the name of the phenomenon to 

 be explained. Thus, for instance, Toletus * gives us the 

 valuable information that ' the substantial form of fire is 

 an active principle by which fire, with heat as its instru- 

 ment, produces fire.' After making this amazing state- 

 ment he recollects that fire is sometimes produced by 

 things other than fire, and he proceeds with grave 

 elaboration to prove that 'fire can result from all the 

 substantial forms capable of producing it in air, in water, 

 or in anything else. ' 



This may be the redudio ad absurdum of the Peripatetic 

 Scholasticism ; for indeed petitio principii could no farther 

 go. It is almost worse than the virtus dormitiva of 

 Moliere's satire. But the author does not appear to have 

 seen the humour of it. Can we wonder, then, that 

 Descartes turned his back upon history ? To him it 

 seemed that an explanation to be an explanation must at 

 least be intelligible. There can be truth and certainty, he 

 thought, only where there is clearness and distinctness. 

 Accordingly all these hidden principles and inexplicable 

 forms must be thrown aside as philosophical lumber, a 

 screen of ignorance and a source of confusion. In true 

 explanation there must be no obscurities, fancies, or 



1 Francisco de Toledo (1532-1596), a Spanish cardinal and theo- 

 logian, author of Summa Casuum Conscientiae. 



