 First, Essence may be taken for the very being of any thing, whereby it is, what it is. And thus the real internal, but generally in Substances, unknown Constitution of Things, whereon their discoverable Qualities depend, may be called their Essence…Secondly,…it being evident, that Things are ranked under Names into sorts or Species, only as they agree to certain abstract Ideas, to which we have annexed those Names, the Essence of each Genus, or Sort, comes to be nothing but that abstract Idea, which the General, or Sortal (if I may have leave so to call it from Sort, as I do General from Genus,) Name stands for. And this we shall find to be that, which the Word Essence imports, in its most familiar use. These two sorts of Essences, I suppose, may not unfitly be termed, the one the Real, the other the Nominal Essence.