11.  Moral and Metaphysical Truth.

Besides truth taken in the strict sense before mentioned, there are other sorts of truths:  As, 1.  Moral truth, which is speaking of things according to the persuasion of our own minds, though the proposition we speak agree not to the reality of things; 2.  Metaphysical truth, which is nothing but the real existence of things, conformable to the ideas to which we have annexed their names.  This, though it seems to consist in the very beings of things, yet, when considered a little nearly, will appear to include a tacit proposition, whereby the mind joins that particular thing to the idea it had before settled with the name to it.  But these considerations of truth, either having been before taken notice of, or not being much to our present purpose, it may suffice here only to have mentioned them.

CHAPTER VI.  OF UNIVERSAL PROPOSITIONS:  THEIR TRUTH AND CERTAINTY.

1.  Treating of Words necessary to Knowledge.

Though the examining and judging of ideas by themselves, their names being quite laid aside, be the best and surest way to clear and distinct knowledge:  yet, through the prevailing custom of using sounds for ideas, I think it is very seldom practised.  Every one may observe how common it is for names to be made use of, instead of the ideas themselves, even when men think and reason within their own breasts; especially if the ideas be very complex, and made up of a great collection of simple ones.  This makes the consideration of words and propositions so necessary a part of the Treatise of Knowledge, that it is very hard to speak intelligibly of the one, 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.