the differences by which they may be distinguished, and the
resemblances by which they ought to be classified; to know, through the
proper evidences of truth, that our ideas, or conceptions, are rightly
conformable to the nature, properties, and relations, of the objects of
which we think; to see how that which is complex may be resolved into its
elements, and that which is simple may enter into combination; to observe
how that which is consequent may be traced to its cause, and that which is
regular be taught by rule; to learn from the custom of speech the proper
connexion between words and ideas, so as to give to the former a just
application, to the latter an adequate expression, and to things a just
description; to have that penetration which discerns what terms, ideas, or
things, are definable, and therefore capable of being taught, and what must
be left to the teaching of nature: these are the essential qualifications
for him who would form good definitions; these are the elements of that
accuracy and comprehensiveness of thought, to which allusion has been made,
and which are characteristic of "the first and highest philosophy."

3. Again, with reference to the cultivation of the mind, I would add: To
observe accurately the appearances of things, and the significations of
words; to learn first principles first, and proceed onward in such a manner
that every new truth may help to enlighten and strengthen the
understanding; and thus to comprehend gradually, according to our capacity,
whatsoever may be brought within the scope of human intellect:--to do these
things, I say, is, to ascend by sure steps, so far as we may, from the
simplest elements of science--which, in fact, are our own, original,
undefinable notices of things--towards the very topmost height of human
wisdom and knowledge. The ancient saying, that truth lies hid, or in the
bottom of a well, must not be taken without qualification; for "the first
and highest philosophy" has many principles which even a child may
understand. These several suggestions, the first of which the Baron de
Puffendorf thought not unworthy to introduce his great work on the Law of
Nature and of Nations, the reader, if he please, may bear in mind, as he
peruses the following digest of the laws and usages of speech.

4. "Definitions," says Duncan, in his Elements of Logic, "are intended to
make known the meaning of words standing for _complex ideas_;[65] and were
we always carefu