WHAT IS EVOLUTION? 25 



human agency, and even the supposed development 

 of the mind of man himself from the powers of lower 

 animals. In these circumstances, if we are to under 

 stand anything of this confused and multiform philo 

 sophy, we must perpetually question its advocates 

 and exponents as to the kind of development of 

 which they are speaking, and as to the causes to 

 which such alleged development may be attributed. 

 We must also be especially cautious in scrutinising 

 any analogies presented to us, as, for example, that 

 between the development of an embryo into a perfect 

 animal, and the succession of animals in geological 

 time. In such a case we must inquire not only if the 

 alleged developments are really similar, but if they 

 take place in similar conditions and under the influ 

 ence of similar causes in other words, whether the 

 analogy is real or only apparent. 



So dangerous is this use of the term evolution, 

 that it may become necessary to abandon the word 

 altogether in purely scientific discussions, and to in 

 sist on the terms causation and development, as cover 

 ing the two distinct ideas now mixed up under evo 

 lution. It is at least necessary in discussions on this 

 subject to be constantly on our guard as to the kind 

 of evolution in question, whether modal evolution of 

 a direct or indirect, literal or figurative character, or 

 the mere figment of a causal evolution. 



With reference to the Darwinian system proper, 

 this kind of definition is not difficult. Darwin s 



