ON THE CONSERVATION OF FORCE. 319 



which mental and moral sciences afford. In the latter it 

 is man in the various phases of his intellectual activity 

 who chains us. Every great deed of which history tells 

 us, every mighty passion which art can represent, every 

 picture of manners, of civic arrangements, of the culture 

 of peoples of distant lands, or of remote times, seizes and 

 interests us, even if there is no exact scientific connec- 

 tion among them. We continually find points of contact 

 and comparison in our own conceptions and feelings; 

 we get to know the hidden capacities and desires of the 

 mind, which in the ordinary peaceful course of civilised 

 life remain unawakened. 



It is not to be denied that, in the natural sciences, this 

 kind of interest is wanting. Each individual fact, taken 

 of itself, can indeed arouse our curiosity or our astonish- 

 ment, or be useful to us in its practical applications. But 

 intellectual satisfaction we obtain only from a connection 

 of the whole, just from its conformity with law. Reason 

 we call tliat faculty innate in us of discovering laws and 

 applying them with thought. For the unfolding of the 

 peculiar forces of pure reason in their entire certainty and 

 in their entire bearing, there is no more suitable arena than 

 inquiry into nature in the wider sense, the mathematics 

 included. And it is not only the pleasure at the success- 

 ful activity of one of our most essential mental powers ; 

 and the victorious subjections to the power of our thought 

 and will of an external world, partly unfamiliar, and partly 

 hostile, which is the reward of this labour ; but there is a 

 kind, I might almost say, of artistic satisfaction, when we 

 are able to survey the enormous wealth of Nature as a 

 regularly-ordered whole — a kosmos, an image of the 

 logical thought of our own mind. 



The last decades of scientific development have led us 

 to the recognition of a new universal law of all natural 

 phenomena, which, from its extraordinarily extended range, 



