EM A NCI PA TION FROM SCIENTIFIC MA TERIA LISM. 429 



been in our possession. Here indeed if anywhere we 

 may fitly apply the words: " Geheimnissvoll offenbar ' : 

 (mysteriously revealed). Daily could we read it and we 

 understood it not. 



When Julius Robert Mayer fifty-three years ago first 

 discovered the equivalency of the various natural forces, or 

 as we now say, the various forms of energy, he had already 

 taken an important step in the critical direction. But 

 according- to an ever-recurrino: law in collective thinking, a 

 new idea is never accepted in the pure and unsullied form 

 in which it is offered. He who has not inwardly experi- 

 enced its development, but who has received the knowledge 

 from without, seeks above all to adapt that which is 

 new as well as possible to his previous notions. In this way 

 the new idea is marred, and, even if not actually perverted, 

 nevertheless robbed of its best power. Indeed so active 

 is this peculiarity of thought that it does not even leave 

 free the discoverer himself. Copernicus' powerful intellect 

 sufficed indeed to cause sun and earth to change places 

 in their motions, but failed to conceive the motions of the 

 other planets in their simplicity ; for these he retained 

 the traditional theory of the epicycles. We see the same 

 thing in Mayer's case. The task of the succeeding genera- 

 tion consisted, as is almost always the case, not simply in 

 reaping the results of the new doctrine, but rather in 

 separating piece by piece the arbitrary and extraneous 

 additions until finally the fundamental idea should appear 

 again in its pure simplicity. 



We observe also in our case a similar development. 

 When J. R. Mayer had set forth the law of equivalency his 

 idea of equivalent transmutability of the different forms of 

 energy was in its simplicity too strange to be directly 

 accepted. Indeed the three scientists to whom we are 

 mostly indebted for the working out of this law — Helm- 

 holtz, W r illiam Thomson and Clausius — all three believed 

 that the law could be " explained " by assuming that the 

 different forms of energy were fundamentally the same, 

 namely, mechanical in nature. In this way what appeared 

 to be the most urgent need was satisfied, namely, a direct 



