230 THE GENESIS OF SCIENCE. 



the arts. Science has been supplying art with truer general! 

 zations and more completely quantitative previsions. Art has 

 been supplying science with better materials and more per 

 fect instruments. And all along the interdependence has been 

 growing closer, not only between art and science, but among 

 the arts themselves, and among the sciences themselves. 



How completely the analogy holds throughout, becomes 

 yet clearer when we recognise the fact that the sciences are 

 arts to each other. If, as occurs in almost every case, the 

 fact to be analyzed by any science, has first to be prepared 

 to be disentangled from disturbing facts by the afore 

 discovered methods of other sciences ; the other sciences 

 so used, stand in the position of arts. If, in solving a dyna 

 mical problem, a parallelogram is drawn, of which the sides 

 and diagonal represent forces, and by putting magnitudes 

 of extension for magnitudes of force a measurable relation 

 is established between quantities not else to be dealt with ; 

 it may be fairly said that geometry plays towards mechan 

 ics much the same part that the fire of the founder plays 

 towards the metal he is going to cast. If, in analyzing the 

 phenomena of the coloured rings surrounding the point of 

 contact between two lenses, a Newton ascertains by calcu 

 lation the amount of certain interposed spaces, far too mi 

 nute for actual measurement ; he employs the science of 

 number for essentially the same purpose as that for which 

 the watchmaker employs tools. If, before writing down 

 his observation on a star, the astronomer has to separate 

 from it all the errors resulting from atmospheric and optical 

 laws, it is manifest that the refraction-tables, and logarithm- 

 books, and formulae, which he successively uses, serve him 

 much as retorts, and filters, and cupels serve the assayer 

 who wishes to separate the pure gold from all accompany 

 ing ingredients. 



So close, indeed, is the relationship, that it is impossi 

 ble to say where science begins and art ends. All the in- 



