EVOLUTION OF MATTER 23 
by Herbert Spencer,* who has perhaps done more than 
any other to establish and emphasize the general ap- 
plicability of the evolution idea. For the law of origin 
by evolution is by no means exclusively confined to 
the method of coming into existence of the species of 
animals and plants. On the contrary, it was equally 
well applied by Spencer himself to describe the manner 
in which are supposed to have arisen the stars and 
other heavenly bodies, the geological strata and geo- 
graphical configuration of the earth, and the various 
gradations of human society. 
The discovery that certain chemical elements exist 
which are themselves not immutable has been made 
since Spencer’s time. Quite recently ‘ the phenomena 
of radio-activity have forced us to believe that radium 
is passing continuously into helium,’t and something 
more than a suspicion has been aroused that radium 
is itself derived from uranium. Thus the dreams of 
the alchemists are shown to have been not wholly 
without foundation, for the probability is strong 
* Spencer gives the following illustration: Regarding the 
striking together of two bodies as a ‘cause,’ he points to the 
following possible ‘effects’: A sound; other vibrations or 
movements in the surrounding air ; a disarrangement of the 
particles of the two bodies in the neighbourhood of the point 
of collision ; the production of heat, and possibly of a spark— 
2.€., of light. 
Two words ‘in this sentence are placed between inverted 
commas, to indicate that they are used in a strictly popular 
sense. The use of the words ‘cause’ and ‘effect,’ though 
seldom strictly scientific, is often convenient, and if used with 
caution, there is no reason why they should lead to misunder- 
standing. See Whetham, ‘The Recent Development of 
Physical Science,’ chapter i. 
t Whetham. 
