MEASUREMENTS 203 



creatures, but in each one of the innumerable cells by which 

 it is constituted, there is found a factor which is absent 

 from all the other objects of external nature ; that is, life. 

 In primitive thought life has usually been identified with 

 the soul, or principle of personality, and it is still quite 

 uncertain whether it ought to be reckoned among objective 

 phenomena, or as something independent. 



Our next step in tracing the general relations between 

 measurement and knowledge leads us to a consideration 

 of what is known as the law of causation, in those of its 

 aspects in which it is affected by the distinction we have 

 drawn between these objects of thought which are, and those 

 which are not measurable ; or, what is the same thing, 

 between ideas which we attribute to the external world 

 and those which we attribute to ourselves. 



That the belief that fire burns is instinctive, and not 

 acquired by repeated experience, is now generally admitted. 

 It is as perfect at first, and upon one instance, as after ever 

 so long a course of experience. Indeed, if it were otherwise, 

 the belief would have been of very small value in the struggle 

 for existence. All but a very few of the pupils would have 

 been killed or maimed in the process of learning the lesson. 

 Its origin may be conjectured with perhaps as great an 

 approach to certainty as that of any of the primitive ten 

 dencies of the mind. The same belief may be inferred from 

 the actions of animals in all grades of evolution. A puppy 

 has been beaten ; the next time it is threatened, the idea 

 of the previous beating is recalled, and is associated with 

 the pain which accompanied it. It begins to whine, or 

 tries to escape, in anticipation of a punishment which perhaps 

 is never inflicted ; and its actions are determined by an 

 unconscious belief in the law of uniform sequence. When 

 a moth returns many times to the candle, the most probable 

 explanation is, either that it altogether forgets its previous 

 acquaintance with the flame, or that its faculty of asso 

 ciation is too feeble to connect in memory the damage it 

 suffered with the flame which occasioned it, and its actions 

 are without the guidance which a sense of the law would 



