procedure from doubt to a sufficient explanation is
to encourage a widespread misapprehension. There could be no greater
error than to suppose that only the senses are used in scientific
investigation. There is no error that men of science are so apt to
resent in the mouths of the non-scientific. Yet they have partly
brought it on themselves by their loose use of the word Induction,
which they follow Bacon in wresting from the traditional meaning of
Induction, using it to cover both Induction or the bringing in of
facts--an affair mainly of Observation--and Reasoning, the exercise of
Nous, the process of constructing satisfactory hypotheses. In reaction
against the popular misconception which Bacon encouraged, it is
fashionable now to speak of the use of Imagination in Science. This is
well enough polemically. Imagination as commonly understood is akin to
the constructive faculty in Science, and it is legitimate warfare to
employ the familiar word of high repute to force general recognition
of the truth. But in common usage Imagination is appropriated to
creative genius in the Fine Arts, and to speak of Imagination
in Science is to suggest that Science deals in fictions, and has
discarded Newton's declaration _Hypotheses non fingo_. In a fight for
popular respect, men of science may be right to claim for themselves
Imagination; but in the interests of clear understanding, the logician
must deplore that they should defend themselves from a charge due
to their abuse of one word by making an equally unwarrantable and
confusing extension of another.

Call it what we will, the faculty of likely guessing, of making
probable hypotheses, of conceiving in all its circumstances the past
situation or the latent and supramicroscopical situation out of
which a phenomenon has emerged, is one of the most important of
the scientific man's special gifts. It is by virtue of it that the
greatest advancements of knowledge have been achieved, the cardinal
discoveries in Molar and Molecular Physics, Biology, Geology, and
all departments of Science. We must not push the idea of stages in
explanatory method too far: the right explanation may be reached in
a flash. The idea of stages is really useful mainly in trying to make
clear the various difficulties in investigation, and the fact that
different men of genius may show different powers in overcoming them.
The right hypothesis may occur in a moment, as if by simple intuition,
but it may be