338 HABIT AND INTELLIGENCE. [chap. 



also where intelligence is most completely dominant that 

 we find those organs, such as the eye and the ear, of which 

 the purpose is the most evident and the most definite, and 

 which appear most completely beyond the power of any 

 merely physical causation to construct. Purpose, as I 

 remarked early in this work, is most traceable where cause 

 is least so. 



In the first chapter of the second volume I shall" have 

 to consider what this organizing intelligence is ; and this 

 will further open the question of the relation between the 

 unconscious life and the mind. 



NOTE A. 



THE OPERATION OF NATURAL SELECTION. 



Why does The first question of an intelligent man when he first hears the 

 selection theory of the Origin of Species by means of natural selection 

 preserve among spontaneous variations, will very probably be something 

 highest ? -^^^^ ^^^ ' — Grranting its postulates, your theory no doubt ac- 

 counts for the origin of different species, one from the other, by 

 descent. But the most important and conspicuous fact in com- 

 paring species and classes is not mere variation, but advance. 

 Granting that natural selection among spontaneous variations is 

 adequate to effect the transition from the Protozoa up to the 

 highest warm-blooded animals, the question stiU remains, why 

 the changes it effects are in this direction % Why does natural 

 selection, or " survival of the fittest," on the average and on the 

 whole, preserve those variations that constitute advance in 

 organisation, and destroy the retrograde ones 1 

 Because I'he answer to this is obvious, and is contained in what has 



the highest "been said already. The most highly organized beings have an 

 efficient, advantage over others in the struggle for existence. Strength 

 of muscle, perfection of the organs of motion and prehension, 

 acuteness of the nerves of sense, perfection of the eye and ear, 

 and increased development of the nervous centres producing 

 mental intelligence, — all these constitute advance in grade of 

 organization, and all at the same time give their possessor an 



