CHAP, ii.] TERMS. 25 



each object as an aggregate of qualities, and acquires the 

 power of dwelling at will upon one or other of those 

 qualities to the exclusion of the rest. Logical abstraction, 

 in short, comes into play, and the mind becomes capable of 

 reasoning, not merely about objects which are physically 

 complete and concrete, but about things which may be 

 thought of separately in the mind though they exist not 

 separately in nature. We can think of the hardness of 

 a rock, or the colour of a flower, and thus produce 

 abstract notions, denoted by abstract terms, which will 

 form a subject for further consideration. 



At the same time arise general notions and classes of 

 objects. We cannot fail to observe that the quality hard- 

 ness exists in many objects, for instance in many fragments 

 of rock ; mentally joining these together, we create the 

 class hard object, which will include, not only the actual 

 objects examined, but all others which may happen to 

 agree with them, as they agree with each other. As our 

 senses cannot possibly report to us all the contents of 

 space, we cannot usually set any limits to the number of 

 objects which may fall into any such class. At this point 

 we begin to perceive the power and generality of thought, 

 which enables us in a single act to treat of indefinitely 

 or even infinitely numerous objects. We can safely assert 

 that whatever is true of any one object coming under a 

 class is true of any of the other objects so far as they 

 possess the common qualities implied in their belonging to 

 the class. We must not place a thing in a class unless 

 we are prepared to believe of it all that is believed of the 

 class in general; but it remains a matter of important 

 consideration to decide how far and in what manner we 

 can safely undertake thus to assign the place of objects in 

 that general system of classification which constitutes the 

 body of science. 



Twofold Meaning of General Names. 



Etymologically the meaning of a name is that which we 

 are caused to think of when the name is used. Now every 

 general name causes us to think of some one or more of 

 the objects belonging to a class ; it may also cause us to 

 think of the common qualities possessed by those objects. 



