Heredity and the Law of Evolution. 285 



having as its result not man's welfare but the necessary develop- 

 ment of the cosmos ; not progress in the purely human sense, and 

 our advance toward perfection, but the advance of the universe 

 toward an ever-increasing complexity may be referred to the 

 laws of mechanics, to the ultimate laws of motion ; and thus the 

 problem of the universe, considered from the standpoint of 

 evolution, becomes a problem of dynamics. 



It would carry us beyond our subject to sketch this antithesis 

 here. It will suffice for us to note its chief features, and to indicate 

 the cause and the law of evolution. 



Considered in general, every evolution may be defined as an 

 integration ; and this explains, in a certain sense, how it is always 

 a transition from less to greater. Its law is the transition from 

 the homogeneous to the heterogeneous, from the uniform to the 

 multiform, from the less to the more coherent, from the indefinite 

 to the definite these various expressions indicating the various 

 aspects of one and the same change, which is essentially identical. 

 Thus it is that in astronomy evolution explains the transition from 

 the almost homogeneous primitive nebulae to our solar system, with 

 its planets and satellites varying so widely in density, velocity and 

 distance from the centre ; in geology, the transition from the rela- 

 tively homogeneous primitive igneous mass to the earth as it is, 

 the surface of which alone appears to us so heterogeneous ; in 

 biology, the transition from the inferior organisms of the primitive 

 ages to the multiform fauna and flora of the present ; in psych- 

 ology, the transition from undeveloped and embryonic forms of 

 mind to states more and more complex ; in sociology, the transition 

 from the simple societies of primitive times to the most complicated 

 and most heterogeneous societies of our epoch ; in history, the 

 development of languages, mechanic arts and fine arts, and their 

 ever multiplying subdivisions. 



Thus evolution consists in an integration, a transition from 

 simple to complex. But this uniform process presupposes some 

 fundamental necessity from which it results. This universal law 

 implies a universal cause. The reason of this universal trans- 

 formation of homogeneous into heterogeneous is this, that every 

 active form produces more than one change, and every cause more 

 than one effect. Thus a shock will produce motion, sound, heat, 



