280 THE PRINCIPLES OF HEREDITY 



448. But while the kind and the amount of development 

 which may result from use in the hand or other physical 

 structures is rigidly limited, a man is capable of learning to 

 use his hand in any one of a thousand or million different 

 ways. Thus he may acquire dexterity as an etcher, a 

 painter, a writer, a watch-maker, a marksman, a blacksmith, 

 a surgeon, and so on in endless variety. But all these 

 acquirements are mental, not physical. We see, then, by 

 contrasting the range of acquirements which use may pro- 

 duce in a hand with the range of acquirements which 

 experience in using a hand may produce in the mind, how 

 immensely greater is the power of making acquirements 

 possessed by the latter. Moreover manual dexterities form 

 only a microscopical part of the total that a man's mind may, 

 and always does, acquire. The artist's skill in guiding his 

 hand is as naught compared to the rest of his mental 

 achievements. As naught to the rest is the skilful penman- 

 ship of the historian, the poet, or the philosopher. Who, in 

 estimating the greatness of the architect or the engineer, 

 even thinks of the skill with which he moves the pencil or 

 the ruler ? Who can even name a manual dexterity which 

 underlies the success of the statesman or the general ? The 

 real adaptability, the real plasticity of man, therefore, lies in 

 his mind, not in his body. It is in the former that he is 

 pre-eminent above lower animals. His body is like a 

 fragment of flint which some rude savage may chip and 

 change a little. His mind is like a mass of clay or metal 

 which a skilful workman may mould into ten thousand 

 shapes. Mentally, much more than physically, man is the 

 product of his immediate surroundings ; whereas physically, 

 much more than mentally, he is the product of a long- 

 extended past. 



449. It is often argued that since men differ greatly as 

 regards their innate physical characters, they must differ as 

 greatly as regards their inborn mental characters. Doubtless 

 this is true. We know, for instance, that of two men 

 similarly trained, one may vastly excel the other as mathe- 

 matician, musician, poet, artist, philosopher, or as commander. 

 But, when it is further argued that the mental differences 

 which we perceive in men are commonly innate in the same 

 sense as their physical differences, the error is obvious. The 

 narrowness of the range of possible physical acquirements 

 arid the width of the range of possibile mental acquirements 

 are not taken into account. The extreme ductility of the 

 mind as compared to the body is forgotten. Beyond a few 



