56 INTRODUCTION 



ideas which are characteristic of a rational being must 

 be analyzed, so that their grounds or premises may be 

 as fully exhibited as possible. And thus the specific 

 quality of a rational soul or self-conscious Monad is * the 

 knowledge of necessary and eternal truths,' that is to 

 say, of the ultimate grounds or premises of all knowledge. 

 The self-conscious Monad represents or perceives the 

 universe in an articulate way. It has carried the internal 

 evolution or realization of the universe so far that its 

 underlying principles have clearly revealed themselves. 

 ' It is by the knowledge of necessary truths and by their 

 abstract expression [leurs abstractions] that we are raised 

 to acts of reflexion which make us think of what is called 

 "I," and observe that this or that is within us : and thus, 

 in thinking of ourselves, we think of being, of substance, 

 of the simple and the compound, of the immaterial and 

 of God Himself, conceiving that what is limited in us 

 is in Him without limits. And these acts of reflexion 

 furnish the chief objects of our reasonings V 



This at once suggests Descartes, but Descartes with 

 a difference. For Leibniz, as for Descartes, the idea of 



principle : whatever I dearly and distinctly perceive regarding anything, 

 that is true or (rightly} predicdble [enuntiabile] of it. For often things 

 which are really obscure and confused seem clear and distinct to 

 men judging hastily. The axiom, therefore, is useless, unless there 

 be added such criteria of the clear and distinct as we have given, 

 and unless there is certainty [constet] regarding the truth of the 

 ideas. For the rest, the rules of common Logic, which are also 

 used in Geometry, are not to be despised as criteria of true state- 

 ments, such rules, for instance, as that nothing should be admitted 

 as certain unless it has been proved by accurate observation 

 [experientid] or by strict demonstration. But strict demonstration 

 is that which keeps to the form prescribed by Logic, not necessarily 

 always in syllogisms set out in order according to the custom of 

 the schools . . . but at least in such a way that the conclusion of 

 the argument follows from its very form. Any right calculation 

 might be taken as an example of an argument of this kind, con- 

 ceived in due form. Therefore no necessary premise must be left 

 out, and all the premises must first have been either proved or 

 assumed by way of hypothesis, in which case the conclusion also is 

 hypothetical. Those who will diligently observe these things will 

 easily guard themselves against deceptive ideas.' 

 1 Monadology, 30. 



