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so long as they conspire in energy, has reached so high a 
position of differentiated integration in a happily-constituted 
and thoroughly- cultivated brain, as to take the form of a com- 
pleted theory of evolution. The theory is demonstrated to the 
mind of an ingenious philosopher. In scientific language, it 
floats in a delightful equipoise of consilient if not jubilant 
brain-cells in the roomy head of its forever famous originator. 
It also finds entrance and makes place for itself in very many 
other nervous organizations sufficiently differentiated to give 
it an answering response of favour. As long as these agencies 
continue in this happy and consentient reaction, the science of 
evolution is accepted as true. But the progress of development 
by its own showing can never rest. No more can any process 
which we commonly call certainty or conviction of truth, the 
exciting agents which in the vulgar speech men call evidence, 
but in scientific nomenclature we must call highly differentiated 
and compactly integrated nerve-cells, which represent the 
theory to be received and the responsive molecules which in 
common speech are unpliysiologically supposed to represent a 
conviction of its truth — neither of these agencies can linger 
long in the happy condition of equilibrium which they have 
attained. Under the onward and upward pressure of manifest 
destiny, they must proceed to other integrations and dif- 
ferentiations which, whether they be beings or phenomena, 
must be unlike those which have preceded them. That phe- 
nomenon which may remain for a while — call it certainty, 
conviction, knowledge, science — long enough to buoy up the 
magnificent theory of evolution, according to the theory and 
under the operation of evolution itself, can have no permanent 
existence, and of course no final and universal authority. Or 
if certainty is still accorded to the lower rank of agencies just 
left behind, the knowledge and the truth, the subjective con- 
viction and the objective reality, may both be superseded by 
some other combination of agencies which is totally unlike 
that which has previously come into being. This is no 
caricature of the theory, but the strictly scientific application 
of its principles. For according to its teachings every thing 
is phenomenal, even the function of knowledge itself. Every 
phenomenon is brought into being and sustained in being, 
and is what it is as a being, by the consentient action of the 
agencies which are concerned in its production. Behind every 
act of knowledge and into every act of knowledge the whole 
universe of force somehow appears. What the phenomenon 
is must depend on the character of the agencies from which 
it is evolved. If the agents change in their so-called consti- 
tution, the reactions must change with them. This must be 
