ix THE DOCTRINE OF IMMORTALITY 195 



thing, or of the extended thing. And Hume's 

 sound common sense led him to defend the thesis 

 which Locke had already foreshadowed, with re- 

 spect to the question of the substance of the soul. 

 Hume enunciates two opinions. The first is that 

 the question itself is unintelligible, and therefore 

 cannot receive any answer; the second is that the 

 popular doctrine respecting the immateriality, 

 simplicity, and indivisibility of a thinking sub- 

 stance is a " true atheism, and will serve to justify 

 all those sentiments for which Spinoza is so 

 universally infamous." 



In support of the first opinion, Hume points 

 out that it is impossible to attach any definite 

 meaning to the word " substance " when employed . 

 for the hypothetical substratum of soul and matter. 

 For if we define substance as that which may 

 exist by itself, the definition does not distinguish 

 the soul from perceptions. It is perfectly easy to 

 conceive that states of consciousness are self-sub- 

 sistent. And, if the substance of the soul is 

 defined as that in which perceptions inhere, what 

 is meant by the inherence? Is such inherence 

 conceivable? If conceivable, what evidence is 

 there of it? And what is the use of a substratum 

 to things which, for anything we know to the 

 contrary, are capable of existing by themselves? 



Moreover, it may be added, supposing the soul 

 has a substance, how do we know that it is differ- 

 ent from the substance, which, on like grounds, 

 156 



