[From NcUurt, Vol. xv.] 



LXXXIV // l.'idwig Ferdinand Helmholtz. 



THE contributions made by Helmholtz to mathematics, physics, physiology, 

 psychology, and aesthetics, are well known to all cultivators of these various 

 subject*. Most of those who have risen to eminence in any one of these 

 have done so by devoting their whole attention to that science ex- 



clusively, so that it is only rarely that the cultivators of different branches can 

 be of service to each other by contributing to one science the skill they have 

 acquired by the study of another. 



Il'iice the ordinary growth of human knowledge is by accumulation round 

 a number of distinct centres. The time, however, must sooner or later arrive 

 when two or more departments of knowledge can no longer remain independent 

 of each other, but must be fused into a consistent whole. But though men 

 of science may be profoundly convinced of the necessity of such a fusion, the 

 operation itself is a most arduous one. For though the phenomena of nature 

 are all consistent with each other, we have to deal not only with these, but 

 with tin- hyjKitheses which have been invented to systematise them ; and it 

 by no means follows that because one set of observers have laboured with all 

 sincerity to reduce to order one group of phenomena, the hypotheses which 

 they have formed will be consistent with those by which a second set of 

 observers have explained a different set of phenomena. Each science may appear 

 tolerably consistent within itself, but before they can be combined into one, 

 each must be stripped of the daubing of untempered mortar by which its parts 

 have been prematurely made to cohere. 



Hence the operation of fusing two sciences into one generally involves much 

 criticism of established methods, and the explosion of many pieces of fancied 

 knowledge which may have been long held in scientific reputation. 



Most of those physical sciences which deal with things without life IKIVC 

 either undergone this fusion or are in a fair state of preparation for it, and 

 the form which each finally assumes is that of a branch of dynamics. 



