Reason and Invention. 845 



memory implies the possibility of two,- and two memories of related 

 things or of the same thing, involve perception and comparison. The 

 simple fact that objects in nature are associated with each other, in- 

 voh es the necessit}' that the sensations of those objects impressed in the 

 brain should be in like manner associated. The ability to see a tree 

 includes also the ability to seo the ground it stands on. The sensations 

 of these two contiguous and related things being constantly formed to- 

 gether in the sensorium, it may happen that an}^ stimulation which 

 revives the memory of one, will overflow to the associated organ and re- 

 vive the memory of the other. The two memories taken together con- 

 stitute a single rational idea ; rational, because the sensations and their 

 memories trul}' represent the relationship which the objects bear to each 

 other. When this relationship is not truly represented in sensation, or 

 memory, the idea is incorrect and unsound. It is in fact irrational, 

 whether its defect arises from partial or false impressions on the sense 

 organs, or from a partial or total failure of the revival of the memory of 

 the sensations. Reason, therefore, is the nervous equivalent of such of 

 the modes of energy as are reflected from objects in our environment, 

 and assail our sense organs. It is the reflection of the environment. It 

 is, so far as it goes, an imitation of external nature. The completeness 

 of the imitation obviously depends upon the number and variety of the 

 sense impressions obtained from the objects imitated. Thus, a person 

 from seeing a tree and the ground it stands on, may get a correct idea 

 of the fact that the tree depends upon the ground for its mechanical sup- 

 port, but without further sense impressions he will know nothing of the 

 roots or of the flowing sap, and if he be color-blind, he may not perceive 

 any difference in color between the leaves and the bark. Our perception of 

 all things, must, in the nature of things, be limited and incomplete in 

 number and variety, and yet in many, and we flatter ourselves in most 

 cases are correct as far as they go. 



But it is evident that the greater number and variet3 T of sense impres- 

 sions we have of any object which serve to furnish us with associated 

 ideas of its related parts, or of its relationship with other objects, the 

 more comprehensive, correct, and rational will our ideas be of such 

 object and its relations. One of the essentials of a comprehensive view 

 of associated objects, is a capacious place for the -storage of the sense 

 impressions. The cerebrum constitutes this storage room in all the ver- 

 tebrates. 



The relative size of this organ in the various animals is a fair gauge of 

 the number of memories which, under proper exposure to sense stimula- 

 tion are possible to them, and consequently of the number of rational 

 ideas of which they are capable. An animal with a limited cerebral 

 capacity has fewer memories in association with each other than man 



