anticipate the particular discoveries which it will make.

Physical research is continually revealing to us new features of
natural processes, and we are thus compelled to search for new forms
of thought appropriate to these features. Hence the importance of a
careful study of those relations between mathematics and Physics which
determine the conditions under which the ideas derived from one
department of physics may be safely used in forming ideas to be
employed in a new department.

The figure of speech or of thought by which we transfer the language
and ideas of a familiar science to one with which we are less
acquainted may be called Scientific Metaphor.

Thus the words Velocity, Momentum, Force, &c. have acquired certain
precise meanings in Elementary Dynamics. They are also employed in
the Dynamics of a Connected System in a sense which, though perfectly
analogous to the elementary sense, is wider and more general.

These generalized forms of elementary ideas may be called metaphorical
terms in the sense in which every abstract term is metaphorical. The
characteristic of a truly scientific system of metaphors is that each
term in its metaphorical use retains all the formal relations to the
other terms of the system which it had in its original use. The
method is then truly scientific--that is, not only a legitimate
product of science, but capable of generating science in its turn.

There are certain electrical phenomena, again, which are connected
together by relations of the same form as those which connect
dynamical phenomena. To apply to these the phrases of dynamics with