s, thoughts, or designs. Such a definition,
he imagines, might have saved Locke, Berkley, and their followers, from
much vain speculation; for with the ideal systems of these philosophers, or
with those of Aristotle and Des Cartes, he by no means coincides. This
author says, "As ideas are the chief materials employed in reasoning and
reflecting, it is of consequence that their nature and differences be
understood. It appears now that ideas may be distinguished into three
kinds: first, Ideas derived from original perceptions, properly termed
_ideas of memory_; second, Ideas communicated _by language_ or other signs;
and third, Ideas _of imagination_. These ideas differ from each other in
many respects; but chiefly in respect to their _proceeding from different
causes_. The first kind is derived from real existences that have been
objects of our senses; _language is the cause of the second_, or any other
sign that has the same power with language; and a man's imagination is to
himself the cause of the third. It is scarce [ly] necessary to add, that an
idea, originally of imagination, being conveyed to others by language or
any other vehicle, becomes in their mind an idea of the second kind; and
again, that an idea of this kind, being afterwards recalled to the mind,
becomes in that circumstance an idea of memory."--_El. of Crit._, Vol. ii,
p. 384.

5. Whether, or how far, language is to the mind itself _the instrument of
thought_, is a question of great importance in the philosophy of both. Our
literature contains occasional assertions bearing upon this point, but I
know of no full or able discussion of it.[30] Cardell's instructions
proceed upon the supposition, that neither the reason of men, nor even that
of superior intelligences, can ever operate independently of words.
"Speech," says he, "is to the mind what action is to animal bodies. Its
improvement is the improvement of our intellectual nature, and a duty to
God who gave it."--_Essay on Language_, p. 3. Again: "An attentive
investigation will show, that there is no way in which the individual mind
can, within itself, to any extent, _combine its ideas_, but by the
intervention of words. Every process of the reasoning powers, beyond the
immediate perception of sensible objects, depends on the structure of
speech; and, in a great degree, according to the excellence of this _chief
instrument of all mental operations_, will be the means of personal
improvement, of the