is founded upon the consent of mankind, which consent arises not 

 of a similar constitution or pre-disposition (and hence a similar 

 relation with the same externals) of their faculties. 



13. If all truth is relative, it might be asked, what assurance 

 have we that things are in reality such as we apprehend them ? 

 that our notions of the external world are correct? There is no 

 other ground of this assurance than our own consciousness or 

 belief. Truth is immutable when the constituents of the relation 

 are the sanae ; it changes when the constituents on either part are 

 varied. If the senses of an individual are constituted differently 

 from those of the rest of his species, his perceptions will be diffe- 

 rent from theirs. If the mind of an individual is elevated by 

 genius or education very much above the level of the rest of his 

 species, his opinions of what is true will be differeiat from theirs. 

 If the taste of an individual is highly cultivated, or peculiarly 

 refined, he will pronounce things to be bad which others esteem. 

 good, and the contrary. 



14. Now if it be asked which of these contradictions is 

 true, I reply, they are all true ; they are all true in regard to 

 those who entertain the respective convictions; but they are not 

 all true with respect to the artificial standard, by which, in a 

 general way, truth is decided by the majority which concur in the 

 same belief. Yet this concurrence is so far from making out a 

 standard by which truth becomes fixed and immutable, that the 

 general belief of nations is many times changed, often reversed, in 

 the course of civilization. This happens in matters of opinion, in 

 taste, in our estimation of good and bad; and it would also happen 

 in matters of sense, if the senses were liable to be changed by 

 education, in the same manner as the understanding is changed. 

 If the descendants of the present race for three generations should 

 be destitute of the sense of hearing, they would l>e very apt to 

 reject, according to the artificial standard, the truth of the 

 existence of sounds; or if their senses should be so changed thai 

 they should be conscious only of some of the abstract, and not of 

 the aggregate, properties of matter, the existence of the spiritual 

 world would be adopted as true, and that of the material would b 

 rejected as false. 



15. In all our attempts, in all our arguments to establish a 

 truth, we aspire only to produce a conviction; and our appeal is 

 successful or not according to the susceptibility of belief, in rela- 

 tion to the proofs which are designed to produce it. The same 

 external objects operating upon, or in relation with, the same 

 senses will produce the same convictions of truth and reality; the 

 propositions which are believed as true by one, will be adopted 

 as true by another, provided they are related with the same con*- 

 stitution of mind. If the senses are modified, the convictions ia 

 regard to the objects with which they are related, are also modified. 

 If the mind is so disposed, it may reject the evidence of a. modified 

 sense, and conclude that it is false, because it is not the accustomed 



