not remain
separate, but now and again reunite in direct and indirect ways. They
inosculate; they severally send off and receive connecting growths; and
the intercommunion has been ever becoming more frequent, more intricate,
more widely ramified. There has all along been higher specialisation,
that there might be a larger generalisation; and a deeper analysis, that
there might be a better synthesis. Each larger generalisation has lifted
sundry specialisations still higher; and each better synthesis has
prepared the way for still deeper analysis.

And here we may fitly enter upon the task awhile since indicated--a
sketch of the Genesis of Science, regarded as a gradual outgrowth from
common knowledge--an extension of the perceptions by the aid of the
reason. We propose to treat it as a psychological process historically
displayed; tracing at the same time the advance from qualitative to
quantitative prevision; the progress from concrete facts to abstract
facts, and the application of such abstract facts to the analysis of new
orders of concrete facts; the simultaneous advance in generalisation and
specialisation; the continually increasing subdivision and reunion of
the sciences; and their constantly improving _consensus_.

To trace out scientific evolution from its deepest roots would, of
course, involve a complete analysis of the mind. For as science is a
development of that common knowledge acquired by the unaided senses and
uncultured reason, so is that common knowledge itself gradually built up
out of the simplest perceptions. We must, therefore, begin somewhere
abruptly; and the most appropriate stage to take for our point of
departure will be the adult mind of the savage.

Commencing thus, without a proper preliminary analysis, we are naturally
somewhat at a loss how to present, in a satisfactory manner, those
fundamental processes of thought out of which science ultimately
originates. Perhaps our argument may be best initiated by the
proposition, that all intelligent action whatever depends upon the
discerning of distinctions among surrounding things. The condition under
which only it is possible for any creature to obtain food and avoid
danger is, that it shall be differently affected by different
objects--that it shall be led to act in one way by one object, and in
another way by another. In the lower orders of creatures this condition
is fulfilled by means of an apparatus which acts automatically. In the
h