Elements of the philosophy of the human mind. By Dugald Stewart. Rev. and abridged, with critical and explanatory notes, for the use of colleges and schools. By Francis Bowen ...

INVENTION. 187
mind, on such occasions, a little less mysterious than it is commonly supposed to be; it may be proper to remark, that the
most copious source of discoveries is the investigation of problems; which seldom fails (even although we should not succeed in the attainment of the object which we have in view) to
exhibit to us some relations formerly unobserved among the
quantities which are under consideration. Of so great importance is it to concentrate the attention to a particular subject,
and to check that wandering and dissipated habit of thought,
which, in the case of most persons, renders their speculations
barren of any profit either to themselves or to others. Many
theorems, too, have been suggested by analogy; many have
been investigated from truths formerly known by altering, or by
generalizing, the hypothesis; and many have been obtained by a
species of induction. An illustration of these various processes
of the mind would not only lead to new and curious remarks,
but would contribute to diminish that blind admiration of original
genius, which is one of the chief obstacles to the improvement
of science.
Success in scientific researches depends on method. -The
history of natural philosophy, before and after the time of Lord
Bacon, affords another proof, how much the powers of invention
and discovery may be assisted by the study of method: and in all
the sciences, without exception, whoever employs his genius with
a regular and habitual success, plainly shows, that it is by means
of general rules that his inquiries are conducted. Of these
rules, there may be many which the inventor never stated
to himself in words; and perhaps he may even be unconscious
of the assistance which he derives from them; but their influence
on his genius appears unquestionably from the uniformity with
which it proceeds; and in proportion as they can be ascertained
by his own speculations, or collected by the logician from an
examination of his researches, similar powers of invention will
be placed within the reach of other men, who apply themselves
to the same study.
The following remarks, which a truly philosophical artist has
applied to painting, may be extended, with some trifling altera