110 THE PROBLEMS OF EVOLUTION 



large part of the literature of this distinctly philo- 

 sophic mode of thought is biologically unsatisfying. 

 The manipulation of words which have special sig- 

 nificance to the manipulator is never wholly satis- 

 factory in science, for the goal of science is to reduce 

 knowledge to the most accurate possible terms of 

 human sense perceptions. The best that we can 

 do to adhere to this worthy purpose is none too 

 good; it should be an ample warning against un- 

 necessary flights of fancy. But a recognition of the 

 serious diflBculties of this field of thought demands 

 that we respect the sincerity with which our more 

 philosophic fellows pursue their investigations, and 

 that we acknowledge in many of their utterances 

 the fairness, the unbiased desire for truth, which 

 we should all strive for. Johnstone's consideration 

 of the matter is an excellent illustration. He con- 

 cludes with these words: "If life is not only energy 

 but also the direction and coordination of energies; 

 if it is a tendency of the same order, but of a dif- 

 ferent direction, from the tendency of inorganic 

 processes, all that biology can usefully do is to 

 inquire into the manner in which this tendency 

 is manifested in material things and energy- 

 transformations. But the tendency itself is some- 

 thing elemental." ^ Wagner formulates a hypoth- 

 esis of neovitalism, an association of a vitalistic 

 principle with a physico-chemical foundation, and 



» The Philosophy of Biology, p. 340, 1914. 



