358 THE POPULAR SCIENCE MONTHLY. 



ideas never arise singly, but are linked together in their origin ; groups 

 of ideas are integrated into trains of thought, and words into correspond- 

 ing trains of sentences to express them. When a stock of ideas has been 

 formed in this manner, the mental growth is mainly carried forward 

 by the establishment of new combinations among them. The simpler 

 ideas pertaining to the objects and actions of the child's environment 

 being once acquired, the development of intelligence consists largely 

 in associating them in new relations and groups of relations. The per- 

 ception of likeness and difference is the essential work that is going 

 on all the time, but the comparisons and discriminations are constantly 

 becoming more extensive, more complex, more minute, and more accu- 

 rate. Thus elementary ideas become fused into one complex idea ; by 

 a still further recognition of likeness and difference, this is associated 

 with a new group, and this again with still larger clusters of associated 

 ideas. 



" That which occurs at this earliest stage of mental growth is ex- 

 actly what takes place in the whole course of unfolding intelligence. 

 Simple as these operations may seem, and begun by the infant as soon 

 as it is born, in their growing complexities they constitute the whole 

 fabric of the intellect. What we call the "mental faculties" are only 

 different modes of the mental activity ; and as one law of growth 

 evolves all the various organs and tissues of the bodily structure, so 

 one law of growth evolves all the diversified " faculties " of the mental 

 structure. Under psychological analysis, the operations of reason, 

 judgment, imagination, calculation, and the acquisitions of the most 

 advanced minds yield at last the same simple elements — the percep- 

 tions of likenesses and differences among things thought about ; while 

 memory is simply the power of reviving these distinctions in con- 

 sciousness. Whatever the object of thought, to know in what re- 

 spects it differs from all other things, and in what respects it resem- 

 bles them, is to know all about it — is to exhaust the action of 

 the intellect upon it. The way the child gets its early knowledge 

 is the way all real knowledge is obtained. When it discovers the 

 likeness between sugar, cake, and certain fruits, that is, when it groups 

 them in thought as siceet, it is making just such an induction 

 as Newton made in discovering the law of gravitation, which was but 

 to discover the likeness among celestial and terrestrial motions. And 

 as with physical objects, so also with human actions. The child may 

 run around the house and play with its toys, but it onust not break 

 things or play with fire. Here, again, are relations of likeness and un- 

 likeness, forming a basis of moral classification. The judge on the 

 bench is constantly doing the same thing ; that is, tracing out the like- 

 nesses of given actions, and classing them as right and wrong." * 



We hence see that by necessity and by the very nature of intelli- 

 gence the movements of mental growth are from the relatively simple 

 * Essay on " The Cultivation of the Observing Powers of Children." (1870.) 



