10 Systems of Equality. Bk. iii. 



not lay much stress upon these prejudices, they 

 must have some tendency to prove that there has 

 been no marked advance in an opposite direction. 



It may perhaps be said, that the w^orld is yet 

 so young, so completely in its infancy, that it 

 ought not to be expected that any difference 

 should appear so soon. 



If this be the case, there is at once an end of all 

 human science. The whole train of reasonings 

 from effects to causes will be destroyed. We 

 may shut our eyes to the book of nature, as it 

 will no longer be of any use to read it. The 

 wildest and most improbable conjectures may be 

 advanced with as much certainty, as the most just 

 and sublime theories, founded on careful and re- 

 iterated experiments. We may return again to 

 the old mode of philosophizing, and make facts 

 bend to systems, instead of establishing systems 

 upon facts. The grand and consistent theory of 

 Newton will be placed upon the same footing as 

 the wild and eccentric hypotheses of Descartes. 

 In short, if the laws of nature be thus fickle and 

 inconstant; if it can be affirmed, and be believed, 

 that they will change, when for ages and ages 

 they have appeared immutable; the human mind 

 will no longer have any incitements to inquiry, 

 but must remain sunk in inactive torpor, or amuse 

 itself only in bewildering dreams and extravagant 

 fancies. 



The constancy of the laws of nature, and of 

 effects and causes, is the foundation of all human 

 knowledge ; and if, without any previous observ- 



