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tions are not relieved from their logical consequences by being 
clothed in the more attractive garb of development or evolu- 
tion, which is borrowed from the sphere of life. ' Especially 
if development itself is conceived as a progress from lower 
to higher potencies of mechanical aggregation, beginning with 
a crystal and ending with a spirit. Development suggests 
associations which are elevated and spiritual. For this reason 
it can be used more readily to dispute and dignify mechanical 
relations and laws. It suggests the variety, the resources, the 
beauty, the intelligence, the joy, and the rapture of living 
beings. It is invested with the associations of mystery, of 
independence and of self-reliance, which are connected with 
living beings, even of lower types. These associations serve 
very largely to explain the otherwise inexplicable fact that 
evolution, even when it has become atheistic or agnostic in its 
philosophy, has entered so easily and been entertained so 
graciously in scientific circles which are high in moral tone 
and devout in religious aspiration. 
It is more than probable that the construction which we 
have placed upon the evolutionist theory of knowledge as 
necessarily suicidal to science, will be regarded as forced and 
unfair. The reductio ad absurdum from the logical conse- 
quences or consistencies of a definition or theory, though 
acknowledged to be theoretically just, is often rejected as 
practically unfair, especially if it can be urged that the advo- 
cate of a theory may perhaps not accept the definition or the 
construction which the critic imposes upon the doctrine which 
he assails. The defender or looker-on will not unfrequently 
interpose in the interest of fair play, and insist that the repre- 
sentative of the theory assailed shall be allowed to define and 
apply his own conceptions. It is always courteous and usually 
just to concede this claim. In the present instance the demand 
can be readily met, and the challenge may be most gratefully 
accepted. We have in his own language the theory of know- 
ledge which is accepted and expounded by the great advocate 
of physiological metaphysics. 
In Herbert Spencer's Principles of Psychology (Introd., 
c. v., vi., vii., part ii., chap, i.), this theory may be found by 
any person who will use the patience to search out its frag- 
mentary and loosely-scattered elements, and carefully adjust 
them into a coherent whole. At first the concession is made, 
and as it would seem with astonishing naivete, which almost 
wins the heart of the critic, not only that psychical phenomena 
are known by consciousness or introspection alone, but that 
science can neither discern nor prove any connection between 
them and any changes in the organism. After this naive con- 
