The vulgar antithesis of fact and theory is founded on a misconception
of the nature of scientific theory, which is, or ought to be, no more
than the expression of fact in a general form. Whatever goes beyond such
expression is hypothesis; and hypotheses are not ends, but means. They
should be regarded as instruments by which new lines of inquiry
are indicated; or by the aid of which a provisional coherency and
intelligibility may be given to seemingly disconnected groups of
phenomena. The most useful of servants to the man of science, they
are the worst of masters. And when the establishment of the hypothesis
becomes the end, and fact is alluded to only so far as it suits the
"Idee," science has no longer anything to do with the business.