For who ever began to build his knowledge on this general proposition, WHAT IS, IS; or, IT IS IMPOSSIBLE FOR THE SAME THING TO BE AND NOT TO BE: and from either of these, as from a principle of science, deduced a system of useful knowledge?
Wrong opinions often involving contradictions, one of these maxims, as a touchstone, may serve well to show whither they lead.

But yet, however fit to lay open the absurdity or mistake of a man's reasoning or opinion, they are of very little use for enlightening the understanding: and it will not be found that the mind receives much help from them in its progress in knowledge; which would be neither less, nor less certain, were these two general propositions never thought on.

It is true, as I have said, they sometimes serve in argumentation to stop a wrangler's mouth, by showing the absurdity of what he saith, [and by exposing him to the shame of contradicting what all the world knows, and he himself cannot but own to be true.] But it is one thing to show a man that he is in an error, and another to put him in possession of truth, and I would fain know what truths these two propositions are able to teach, and by their influence make us know which we did not know before, or could not know without them.

Let us reason from them as well as we can, they are only about identical predications, and influence, if any at all, none but such.
Each particular proposition concerning identity or diversity is as clearly and certainly known in itself, if attended to, as either of these general ones: [only these general ones, as serving in all cases, are therefore more inculcated and insisted on.] As to other less general maxims, many of them are no more than bare verbal propositions, and teach us nothing but the respect and import of names one to another.
'The whole is equal to all its parts:' what real truth, I beseech you, does it teach us?
What more is contained in that maxim, than what the signification of the word TOTUM, or the WHOLE, does of itself import?
And he that knows that the WORD whole stands for what is made up of all its parts, knows very little less than that the whole is equal to all its parts.

And, upon the same ground, I think that this proposition, 'A hill is higher than a valley', and several the like, may also pass for maxims.