 But it being evident, that things are ranked under Names into sorts or Species…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. (Bk.III, Ch.III, 15)