II THE PROGRESS OF SCIENCE 103 



so far as I know, it is the first attempt to deal, on 

 scientific principles, with modern scientific facts 

 and speculations. For the " Philosophic positive " 

 of M. Comte, with which Mr. Spencer's system of 

 philosophy is sometimes compared, though it 

 professes a similar object, is unfortunately per- 

 meated by a thoroughly unscientific spirit, and its 

 author had no adequate acquaintance with the 

 physical sciences even of his own time. 



The doctrine of evolution, so far as the present 

 physical cosmos is concerned, postulates the fixity 

 of the rules of operation of the causes of motion 

 in the material universe. If all kinds of matter 

 are modifications of one kind, and if all modes of 

 motion are derived from the same energy, the 

 orderly evolution of physical nature out of one 

 substratum and one energy implies that the rules 

 of action of that energy should be fixed and 

 definite. In the past history of the universe, 

 back to that point, there can be no room for 

 chance or disorder. But it is possible to raise 

 the question whether this universe of simplest 

 matter and definitely operating energy, which 

 forms our hypothetical starting point, may not 

 itself be a product of evolution from a universe of 

 such matter, in which the manifestations of 

 energy were not definite in which, for example, 

 our laws of motion held good for some units and 

 not for others, or for the same units at one time 



