without explaining the other.

2. General Truths hardly to be understood, but in verbal Propositions.

All the knowledge we have, being only of particular or general truths,
it is evident that whatever may be done in the former of these, the
latter, which is that which with reason is most sought after, can never
be well made known, and is very seldom apprehended, but as conceived
and expressed in words. It is not, therefore, out of our way, in the
examination of our knowledge, to inquire into the truth and certainty of
universal propositions.

3. Certainty twofold--of Truth and of Knowledge.

But that we may not be misled in this case by that which is the danger
everywhere, I mean by the doubtfulness of terms, it is fit to observe
that certainty is twofold: CERTAINTY OF TRUTH and CERTAINTY OF
KNOWLEDGE. Certainty of truth is, when words are so put together in
propositions as exactly to express the agreement or disagreement of the
ideas they stand for, as really it is. Certainty of knowledge is to
perceive the agreement or disagreement of ideas, as expressed in any
proposition. This we usually call knowing, or being certain of the truth
of any proposition.

4. No Proposition can be certainly known to be true, where the real
Essence of each Species mentioned is not known.

Now, because we cannot be certain of the truth of any general
proposition, unless we know the precise bounds and extent of the species
its terms stand for, it is necessary we should know the essence of each
species, which is that which constitutes and bounds it.

This, in all simple ideas and modes, is not hard to do. For in these
the real and nominal essence being the same, or, which is all one, the
abstract idea which the general term stands for being the sole essence
and boundary that is or can be supposed of the species, there can be no
doubt how far the species extends, or what things are comprehended under
each term; which, it is evident, are all that have an exact conformity
with the idea it stands for, and no other. But in substances, wherein
a real essence, distinct from the nominal, is supposed to constitute,
determine, and bound the species, the extent of the general word is very
uncertain; because, not knowing this real essence, we cannot know what
is, or what is not of that species; and, consequently, what may or may
not with certainty be affirmed of it. And thus, speaking of a MAN,
or GOLD, or any other species of natural subs