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 ...

136 ABSTRACTION.
our animal strength acquires by the use of mechanical engines,
exhibits but a faint image of that increase of our intellectual
capacity which we owe to language. It is this increase of our
natural powers of comprehension, which seems to be the principal foundation of the pleasure we receive from the discovery
of general theorems. Such a discovery gives us at once the
command of an infinite variety of particular truths, and conlmunicates to the mind a sentiment of its own power, not unlike
to what we feel when we contemplate the magnitude of those
physical effects, of which we have acquired the command by
our mechanical contrivances.
It may perhaps appear, at first, to be a further consequence
of the principles I have been endeavoring to establish, that the
difficulty of philosophical discoveries is much less than is commonly imagined; but the truth is, it only follows from them,
that this difficulty is of a different nature from what we are apt
to suppose, on a superficial view of the subject. To employ,
with skill, the very delicate instrument which nature has made
essentially subservient to general reasoning, and to guard
against the errors which result from an injudicious use of it,
require an uncommon capacity of patient attention, and a
cautious circumspection in conducting our various intellectual
processes, which can only be acquired by early habits of philosophical reflection. To assist and direct us in mlaking this acquisition ought to form the most important branch of a rational
logic; a science of far more extensive utility, and of which the
principles lie much deeper in the philosophy of the human
mind, than the trifling art which is commonly dignified with
that name. The branch in particular to which the foregoing
observations more immediately relate, must for ever remain in
its infancy, till a most difficult and important desideratum in
the history of the mind is supplied, by an explanation of the
gradual steps by which it acquires the use of the various classes
of words which compose the language of a cultivated and enlightened people. Of some of the errors of reasoning to which
we are exposed by an incautious use of words, I took notice in
the preceding section; and I shall have occasion afterwards to