nd pass into the practical.
Let us therefore inquire what constitutes the feeling of rationality in
its _practical_ aspect. If thought is not to stand forever pointing at
the universe in wonder, if its movement is to be diverted from the
issueless channel of purely theoretic contemplation, let us ask what
conception of the universe will awaken active impulses capable of
effecting this diversion. A definition of the world which will give
back to the mind the free motion which has been blocked in the purely
contemplative path may so far make the world seem rational again.

Well, of two conceptions equally fit to satisfy the logical demand,
that one which awakens the active {76} impulses, or satisfies other
aesthetic demands better than the other, will be accounted the more
rational conception, and will deservedly prevail.

There is nothing improbable in the supposition that an analysis of the
world may yield a number of formulae, all consistent with the facts.
In physical science different formulae may explain the phenomena
equally well,--the one-fluid and the two-fluid theories of electricity,
for example. Why may it not be so with the world? Why may there not
be different points of view for surveying it, within each of which all
data harmonize, and which the observer may therefore either choose
between, or simply cumulate one upon another? A Beethoven
string-quartet is truly, as some one has said, a scraping of horses'
tails on cats' bowels, and may be exhaustively described in such terms;
but the application of this description in no way precludes the
simultaneous applicability of an entirely different description. Just
so a thorough-going interpretation of the world in terms of mechanical
sequence is compatible with its being interpreted teleologically, for
the mechanism itself may be designed.

If, then, there were several systems excogitated, equally satisfying to
our purely logical needs, they would still have to be passed in review,
and approved or rejected by our aesthetic and practical nature. Can we
define the tests of rationality which these parts of our nature would
use?

Philosophers long ago observed the remarkable fact that mere
familiarity with things is able to produce a feeling of their
rationality. The empiricist school has been so much struck by this
circumstance {77} as to have laid it down that the feeling of
rationality and the feeling of familiarity are one and the same thing,
and t