NEW ESSAYS 363 



and night into day. But they would have been wrong 

 if they had thought that the same rule is observed 

 everywhere else 25 , for since that time, the opposite has 

 been experienced 26 by people on a visit to Nova Zembla. 

 And he would still be wrong who should think that, in 

 our regions at least, it is a necessary and eternal truth 

 that shall endure for ever 27 , since we must hold that the 

 earth and the sun itself do not exist necessarily, and that 

 perhaps there will come a time when this beautiful star 

 with its whole system will no longer exist, at least in its 

 present form 28 . Whence it seems that necessary truths, 

 such as we find in pure mathematics and especially in 

 arithmetic and geometry, must have principles whose 

 proof does not depend upon instances nor, consequently, 

 upon the witness of the senses, although without the 

 senses it would never have come into our heads to think 

 of them. This is a point which should be carefully noted, 

 and it is one which Euclid so well understood that he 

 often proves by reason that which is evident enough 

 through experience and through sense-images' 29 . Logic 

 also, along with metaphysics and ethics [la morale], of 

 which the one forms natural theology 30 and the other 

 natural jurisprudence, are full of such truths ; and con- 

 sequently their demonstration 31 can come only from the 



25 E. omits < else/ . 26 E. reads seen/ 



37 E. omits ' that shall endure for ever/ 



28 Cf. Monadology, 28. 



29 Cf. the letter to Queen Sophia Charlotte, quoted above : < The 

 senses can indeed in a way make known to us that which is, but 

 they cannot make known that which ought to be or which cannot 

 be otherwise. . . . The senses and inductions never yield us truth 

 perfectly universal nor that which is absolutely necessary, but only 

 that which is and that which occurs in particular instances.' 

 (G. vi. 504, 505.) 



so i True metaphysics is hardly different from true logic, that is 

 to say, from the art of discovery in general ; for in fact metaphysics 

 is natural theology, and the same God, who is the source of all good 

 things, is also the principle of all parts of knowledge.' Lettre a la 

 Princesse Sophie (undated) (G. iv. 292). 



31 i.e. the certainty of logic, metaphysics and ethics as sciences. 



