ESTIMATE OF LEIBNIZ'S PHILOSOPHY 1 6 1 



matter, of thought and external existence, Descartes could 

 not rest satisfied with the idea of a most perfect being. He 

 must get beyond the idea to the reality ; he must justify 

 not one or another idea but thought itself. In the charac- 

 teristics of * clearness ' and * distinctness ' in ideas he had 

 found a criterion for the consistency of thought with itself. 

 A clear and distinct idea completely satisfied thought, but 

 it still remained to be shown that such an idea has 

 objective validity ; that there actually exists that which it 

 represents. Now according to Descartes, it is the truth- 

 fulness, the consistency, the goodness of an actually 

 existing God (who would not be perfect had He not these 

 qualities) that assure to us the validity of our clear and 

 distinct ideas. ' Even the principle,' says Descartes, 

 ' which I have already taken for a rule, namely, that all 

 the things which we clearly and distinctly conceive are 

 true, is certain only because God is or exists, and because 

 He is a perfect Being, and because all that we possess is 

 derived from Him. ... If we did not know that all which 

 we possess of real and true proceeds from a perfect and 

 infinite Being, however clear and distinct our ideas might 

 be, we should have no ground on that account for the 

 assurance that they possessed the perfection of being true '.' 

 Accordingly, as regards real existence (apart from that of 

 the pure Ego), everything in Descartes's system ultimately 

 turns upon this unexplained principle of cause, by means 

 of which he proves the existence of God, and which he 

 again employs in establishing the reality of the world. 

 God must exist, for otherwise no adequate cause can be 

 assigned for the existence of the idea of God in us. And 

 again, we must postulate the real existence of external 



1 Method, Part iv. (Veitch's Tr., p. 80). Cf. Meditation IV: 'It is 

 impossible that God should ever deceive me ; since in all fraud 

 and deceit one meets with some kind of imperfection ; and 

 although it may seem that to be able to deceive is a mark of clever- 

 ness or of power, the wish to deceive always indicates, without 

 a doubt, feebleness or malice ; and accordingly such a wish cannot 

 exist in God.' Cf. Hegel, Geschichte der Phil. iii. p. 319. 



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