102 THE ARREST OF THE BODY. 



Is the Hand then finished ? Can Nature take out 

 no new patent in this direction ? Is the fact that no 

 novelty is introduced in the case of Man a proof that 

 the ultimate Hand has appeared? By no means. 

 And yet it *is probable for other reasons that the 

 ultimate Hand has appeared ; that there will never be 

 a more perfectly handed animal than Man. And 

 why? Because the causes which up to this point 

 have furthered the evolution of the Hand have begun 

 to cease to act. In the perfecting of the bodily 

 organs, as of all other mechanical devices, necessity is 

 the mother of invention. As the Hand was given 

 more and more to do, it became more and more 

 adapted to its work. Up to a point, it respond- 

 ed directly to each new duty that was laid upon 

 it. But only up to a point. There came a time 

 when the necessities became too numerous and too 

 varied for adaptation to keep pace with them. And 

 the fatal day came, the fatal day for the Hand, when 

 he who bore it made a new discovery. It was the 

 discovery of Tools. Henceforth what the Hand used 

 to do, and was slowly becoming adapted to do better, 

 was to be done by external appliances. So that if 

 anything new arose to be done, or to be better done, 

 it was not a better Hand that was now made but a 

 better tool. Tools are external Hands. Levers are 

 the extensions of the bones of the arm. Hammers are 

 callous substitutes for the fist. Knives do the work 

 of nails. The vice and the pincers replace the fin- 

 gers. The day that Cave-man first split the marrow 

 bone of a bear by thrusting a stick into it, and strik- 

 ing it home with a stone that day the doom of the 

 Hand was sealed. 



