EVOLUTION AND THE PRESENT AGE 275 
tions was much more Lamarckian than Darwinian; 
that is to say, he attributed far greater importance to 
such agencies as the cumulative effects of use and 
disuse than Darwin ever did; but when Darwin’s 
great work appeared, Spencer cordially welcomed 
him as a most powerful auxiliary. Spencer’s next 
achievement was to point out some of the most 
essential features in the development of mankind 
as socially organized, and to make it practically 
certain that with the further advance of knowledge 
this group of phenomena also will be embraced under 
the one great law of evolution. And there was still 
one thing more which Spencer may fairly be said to 
have accomplished. The generalization of the meta- 
morphosis of forces which was begun a century ago by 
Count Rumford when he recognized heat as a mode of 
molecular motion was consummated about the middle 
of the century, when Dr. Joule showed mathematically 
just how much heat is equivalent to just how much 
visible motion, and when the researches of Helmholtz, 
Mayer, and Faraday completed the grand demonstra- 
tion that light and heat and magnetism and electricity 
and visible motion are all interchangeable one into the 
other, and are continually thus interchanging from 
moment to moment. 
Now Spencer showed that the universal process 
of evolution as described in his formula not only 
conforms to the development of an individual life as 
generalized by von Baer, but is itself an inevitable 
consequence of the perpetual metamorphosis of energy 
that was detected by the great thinkers above 
named, from Rumford to Helmholtz. Had he only 
accomplished the former part of the task, his place in 
