854 Dynamic TJieory. 



smirched hands had innumerable times left their shapes on other objects. 

 It was at last discerned that an illiterate king could print his name 

 with a seal, when he could not write it. With such hints before their 

 ej'es for two thousand years, men nevertheless, continued to copy their 

 books with slow and costly manual toil. 



When we consider how great their need was for this art, when we 

 consider that all the mechanical principles necessary for its performance 

 had long been familiarly known, that those required to be applied were 

 few, and their application exceedingly simple, we must be far more 

 struck b} r man's stupidity than by his fertility of invention.. 



Cotton has been cultivated certainly for five or six thousand years, 

 and has been almost the only material for clothing possessed by numer- 

 ous nations. It has always been a most serious task to separate the 

 cotton fiber from the seed. For the five or six thousand years in ques- 

 tion, men did this by hand, and to pull the seeds out of two pounds of 

 fiber made a day's work for an active man or woman. Men had pos- 

 sessed saws for at least as long a time, and were familiar with their use 

 and- action in pulling out woody fiber from a board, or stick of wood. 

 But it seems never to have occurred to anyone during all these ages, 

 that they might reduce their labor in getting their clothes several hun- 

 dred per cent, by applying the saw to pulling the cotton fiber away from 

 the seed. It only needed that the saw teeth should draw the fiber 

 through a crack too narrow to allow the seed to follow. So obvious 

 and simple is this, since Whitney has shown it to us, that we can only 

 be astonished at the dense and costly dulness of perception that so long 

 ignored it. 



Numerous examples might be cited to prove that all new inventions 

 are adaptations of old instruments, or at least, of old principles, to new 

 purposes ; and the amount of the modification of the instrument is sel- 

 dom very great in any one case or by any one individual. And it may 

 be truly asserted that every new association of ideas, under the influence 

 of which experiments and adaptations are made, is brought about by 

 causes extrinsic to the inventor and so far as he is concerned, purely 

 accidental. 



The growth of all machines is an evolution, and if they be great and 

 complicated their growth is slow, and passes through many stages of de- 

 velopment ; and they receive improvements and alterations from many 

 hands, and usually but small ones from any one. 



Original scientific discovery is accomplished simply by the investi- 

 gator putting himself in a condition to see whatever there is to be seen. 

 He does not know beforehand what that is to be. So far as he is con- 

 cerned, the discovery is accidental. 



A few individuals have made what are called extensive discoveries of 



