The Stromata: Book VIII 8The Method of Classifying Things and Names.

In language there are three things:--Names, which are primarily the symbols of conceptions, and by consequence also of subjects. Second, there are Conceptions, which are the likenesses and impressions of the subjects. Whence in all, the conceptions are the same; in consequence of the same impression being produced by the subjects in all. But the names are not so, on account of the difference of languages. And thirdly, the Subject-matters by which the Conceptions are impressed in us.

The names are reduced by grammar into the twenty-four general elements; for the elements must be determined. For of Particulars there is no scientific knowledge, seeing they are infinite. But it is the property of science to rest on general and defined principles. Whence also Particulars are resolved into Universals. And philosophic research is occupied with Conceptions and Real subjects. But since of these the Particulars are infinite, some elements have been found, under which every subject of investigation is brought; and if it be shown to enter into any one or more of the elements, we prove it to exist; but if it escape them all, that it does not exist.

Of things stated, some are stated without connection; as, for example, "man" and "runs," and whatever does not complete a sentence, which is either true or false. And of things stated in connection, some point out "essence," some "quality," some "quantity," some "relation," some "where," some "when," some "position," some "possession," some "action," some "suffering," which we call the elements of material things after the first principles. For these are capable of being contemplated by reason.

But immaterial things are capable of being apprehended by the mind alone, by primary application.

And of those things that are classed under the ten Categories, some are predicated by themselves (as the nine Categories), and others in relation to something.

And, again, of the things contained under these ten Categories, some are Univocal, as ox and man, as far as each is an animal. For those are Univocal terms, to both of which belongs the common name, animal; and the same principle, that is definition, that is animate essence. And Heteronyms are those which relate to the same subject under different names, as ascent or descent; for the way is the same whether upwards or downwards. And the other species of Heteronyms, as horse and black, are those which have a different name and definition from each other, and do not possess the same subject. But they are to be called different, not Heteronyms. And Polyonyms are those which have the same definition, but a different name, as, hanger, sword, scimitar. And Paronyms are those which are named from something different, as "manly" from "manliness."

Equivocal terms have the same name, but not the same definition, as man--both the animal and the picture. Of Equivocal terms, some receive their Equivocal name fortuitously, as Ajax, the Locrian, and the Salaminian; and some from intention; and of these, some from resemblance, as man both the living and the painted; and some from analogy, as the foot of Mount Ida, and our foot, because they are beneath; some from action, as the foot of a vessel, by which the vessel sails, and our foot, by which we move. Equivocal terms are designated from the same and to the same; as the book and scalpel are called surgical, both from the surgeon who uses them and with reference to the surgical matter itself.