First, when the mind supposes any idea it has conformable to that in other men’s minds, called by the same common name; v.g. when the mind intends or judges its ideas of justice, temperance, religion, to be the same with what other men give those names to.

Secondly, when the mind supposes any idea it has in itself to be conformable to some real existence.  Thus the two ideas of a man and a centaur, supposed to be the ideas of real substances, are the one true and the other false; the one having a conformity to what has really existed, the other not.  Thirdly, when the mind refers any of its ideas to that real constitution and essence of anything, whereon all its properties depend:  and thus the greatest part, if not all our ideas of substances, are false.

6.  The cause of such Reference.

These suppositions the mind is very apt tacitly to make concerning its own ideas.  But yet, if we will examine it, we shall find it is chiefly, if not only, concerning its abstract complex ideas.  For the natural tendency of the mind being towards knowledge; and finding that, if it should proceed by and dwell upon only particular things, its progress would be very slow, and its work endless; therefore, to shorten its way to knowledge, and make each perception more comprehensive, the first thing it does, as the foundation of the easier enlarging its knowledge, either by contemplation of the things themselves that it would know, or conference with others about them, is to bind them into bundles, and rank them so into sorts, that what knowledge it gets of any of them it may thereby with assurance extend to all of that sort; and so advance by larger steps in that which is its great business, knowledge.  This, as I have elsewhere shown, is the reason why we collect things under comprehensive ideas, with names annexed to them, into genera and species; i.e. into kinds and sorts.

7.  Names of things supposed to carry in them knowledge of their essences.

If therefore we will warily attend to the motions of the mind, and observe what course it usually takes in its way to knowledge, we shall I think find, that the mind having got an idea which it thinks it may have use of either in contemplation or discourse, the first thing it does is to abstract it, and then get a name to it; ans so lay it up in its storehouse, the memory, as containing the essence of a sort of things, of which that name is always to be the mark.  Hence it is, that we may often observe that, when any one sees a new thing of a kind that he knows not, he presently asks, what it is; meaning by that inquiry nothing but the name.  As if the name carried with it the knowledge of the species, or the essence of it; whereof it is indeed used as the mark, and is generally supposed annexed to it.

8.  How men suppose that their ideas must correspond to things, and to the customary meanings of names.