For what information, what knowledge, carries this proposition in it, viz.

'Lead is a metal' to a man who knows the complex idea the name lead stands for?
All the simple ideas that go to the complex one signified by the term metal, being nothing but what he before comprehended and signified by the name lead.

Indeed, to a man that knows the signification of the word metal, and not of the word lead, it is a shorter way to explain the signification of the word lead, by saying it is a metal, which at once expresses several of its simple ideas, than to enumerate them one by one, telling him it is a body very heavy, fusible, and malleable.
5.

As part of the Definition of the Term Defined.
Alike trifling it is to predicate any other part of the definition of the term defined, or to affirm anyone of the simple ideas of a complex one of the name of the whole complex idea; as, 'All gold is fusible.' For fusibility being one of the simple ideas that goes to the making up the complex one the sound gold stands for, what can it be but playing with sounds, to affirm that of the name gold, which is comprehended in its received signification?
It would be thought little better than ridiculous to affirm gravely, as a truth of moment, that gold is yellow; and I see not how it is any jot more material to say it is fusible, unless that quality be left out of the complex idea, of which the sound gold is the mark in ordinary speech.

What instruction can it carry with it, to tell one that which he hath been told already, or he is supposed to know before?
For I am supposed to know the signification of the word another uses to me, or else he is to tell me.