ii THE CONTENTS OF THE MIND 75 



tive arguments. He may be right or wrong; but 

 the most he, or anybody else, can prove in favour 

 of his conclusion is, that we know nothing more 

 of the mind than that it is alseries of perceptions. *> 

 Whether there is something in the mind that lies 

 beyond the reach of observation; or whether per- 

 ceptions themselves are the products of something 

 which can be observed and which is not mind; 

 are questions which can in nowise be , settled by 

 direct observation. Elsewhere, the objectionable 

 hypothetical element of the definition of mind is 

 less prominent: 



" The true idea of the human mind is to consider it as a 

 system of different perceptions, or different existences, 

 which are linked together by the relation of cause and 

 effect, and mutually produce, destroy, influence and modify 

 each other. ... In this respect I cannot compare the soul 

 more properly to anything than a republic or common- 

 wealth, in which the several members are united by the 

 reciprocal ties of government and subordination, and give 

 rise to other persons who propagate the same republic in 

 the incessant changes of its parts." (I. p. 331.) 



But, leaving the question of the proper defini- 

 tion of mind open for the present, it is further a 

 matter of direct observation, that, when we take 

 a general survey of all our perceptions or states of 

 consciousness, they naturally fall into sundry 

 groups or classes. Of these classes, two are 

 distinguished by Hume as of primary importance. 

 All " perceptions," he says, are either "Impres- 

 sions " or " Ideas." 



