180 



HABIT AND INTELLIGENCE. 



[chap. 



Voluntary 



actions 



may 



become 



habitual. 



This will 

 not ac- 

 count for 

 all ha,bits. 



Question 

 of the 

 origin of 

 species. 



of actions that has become habitual — just as the laws of 

 motiou, though they are perfectly well understood, throw 

 no light on the origin of force. We know that in man, 

 and in a less degree among the more intelligent animals, a 

 great variety of actions are capable of becoming habitual 

 that were voluntary in their origin. On this possibility 

 the whole art of education is founded. But this explana- 

 tion will evidently not apply to the facts of what I have 

 called spontaneous variation ; nor will it apply to any 

 formative habit whatever, nor to such motor habits as the 

 cell-building instinct of the bee, or the turning and twining 

 instinct of the Passifiora gracilis, mentioned above. By 

 the definition of habit that I have adopted, all specific 

 characters are habits ; and, in this sense, the question of 

 the origin of particular habits includes the whole vast and 

 enigmatic subject of the origin of species. But, little as 

 that subject is understood, recent research and speculation 

 have let a few rays of light into the darkness. 



Summary _ 

 Habit. 



Heredi- 

 tary trans- 

 mission. 



Variation. 



Disuse. 



Promi- 

 nence. 



Tenacity. 



We may thus sum up the laws of habit : — 



All vital actions — formative, motor, and mental — tend 

 to become habitual 



All characters tend to become hereditary. An acquired 

 character, when transmitted to offspring, appears some- 

 times at the same age at which it appeared in the parent, 

 sometimes earlier. 



All characters are in some degree variable, and particular 

 characters may acquire a habit of varying. 



The foregoing three are the elementary laws of habit; 

 the following are derived as corollaries from them : — 



Habits, being formed by use, are weakened and destroyed 

 by disuse. 



The promineTWG of a habit, or its present strength, depends 

 on its having been recently exercised. 



The tenacity of a habit, or the difficulty of destroying it, 

 depends on its having been long exercised. 



Consequently, a prominent habit may disappear, while a 

 tenacious, perhaps a hereditary one, survives it. 



A habit may become latent, and reappear. The re- 



