IDEAS. 35 



Now in this classification, notwithstanding that it is 

 needful to quote at least ten distinct terms which arc cither 

 now in use among ps)'chologists or have been used by 

 classical English writers upon these topics, we may observe 

 that there arc really but three separate classes to be 

 distinguished. Moreover, it will be noticed that, for the 

 sake of definition, I restrict the first three terms to denote 

 memories of particular sensuous perceptions — refusing, there- 

 fore, to apply them to those blended memories of many 

 sensuous perceptions which enable animals and infants (as 

 well as ourselves) to form compound ideas of kind or class 

 without the aid of language. Again, the first division of 

 this threefold classification has to do only with what are 

 termed percepts, while the last has to do only with what 

 are termed concepts. Now there does not exist any 

 equivalent word to meet the middle division. And this fact 

 in itself shows most forcibly the state of ambiguous confusion 

 into which the classification of ideas has been wrought. 

 Psychologists of both the schools that we are considering — 

 namely, those who maintain and those who deny that there 

 is any difference of kind between the ideation of men and 

 animals — are equally forced to allow that there is a great 

 difference between what I have called a simple idea and what 

 I have called a compound idea. In other words, it is a 

 matter of obvious fact that the only distinction between ideas 

 is not that between the memory of a particular percept and 

 the formation of a named concept ; for between these two 

 classes of ideas there obviously lies another class, in virtue 

 of which even animals and infants are able to distinguish 

 individual objects as belonging to a sort or kind. Yet this 

 large and important territory of ideation, lying between the 

 other two, is, so to speak, unnamed ^ro ind. Even the words 

 " compound idea," " complex idea," and " mixed idea," arc by 

 me restricted to it without the sanction of previous usage ; 

 for, as above remarked, so completely has the existence of 

 this intermediate land been ignored, that \vc have no word 

 at all which is applicable to it in the same way that Percept 



