XXXIV.] iMENTAL GROWTH. 85 • 



which we have uow attamed, this axiom may be thus 

 amplified : — " There is nothing in the organism but what it 

 has received in the food, except the organizing principle of 

 vital intelligence which builds up the organism ; and there 

 is nothing in the mind but what it has received from 

 sensation, except the organizing principle of mental intel- 

 ligence, which evolves knowledge out of the materials 

 received from sensation." It is my belief that the 

 organizing intelligence of the vital organism, and the in- 

 telligence of the mind, are one and the same principle, 

 though acting unconsciously in the organism and con- 

 sciously in the mind : and further, that this intelligence, 

 under both of these its manifestations, is an ultimate fact, 

 incapable of being resolved into anything simpler than 

 itself. 



I have not yet, however, fully stated the closeness of the 

 analogy between organic growth and laental growth. The 

 living organism, while it is constantly acquiring and 

 assimilating new material, is as constantly parting with Assimila- 

 old material. These two processes respectively consti- ^°g J^*^ ' 

 tute nutrition and waste ; and the excess of nutrition over 

 waste constitutes growth. Waste is most rapid in the 

 early youth of an organism, but at that period nutrition both most 

 is more rapid still, and consequently growth is most rapid youth.^'^ 

 in early youth. The process of mental growth is an exact 

 parallel to this. The mind is constantly receiving impres- Parallel in 

 sions from the external senses, and as constantly losing ^''^'^emng 

 the impressions by forgetting them ; old impressions on getting 

 the memory fade away and are lost, and new ones supply ^/essionT" 

 their place ; and mental growth consists in the excess of 

 what is remembered over what is forgotten : mental growth Organic 

 goes on so long as the new impressions which are re- '^r^^^+h"*^^^ 

 tained exceed in number, force, and' variety those which both con- 

 are lost. As organic growth consists in the organism excess of 

 acquiring more substance than it parts with, so mental '*^'^*^t i'"*, 



. . . -^ received 



growth consists m the imnd acquirmg more and stronger over what 

 impressions than it loses. ^® ^°**- 



This, when once distinctly stated, is self-evident ; but 

 the parallel is closer still. Waste, no less than nutrition, 



