In this irreversible catena proceeding from ground to consequent, we have left far behind such things as the formal parity of genus and differentia considered as falling under the same predicable, 3 and hence justified in part Porphyry's divergence from the scheme of predicables.
It is this definitely rational tone that constitutes the differentia of the teaching of the sages.
Arsenic, may be placed in either division, their properties approximating to both metallic and non-metallic. One chemical differentia utilizes the fact that metals always form at least one basic oxide which yields salts with acids, while nonmetals usually form acidic oxides, i.e.
Henceforth a significant differentia Gratian.
This classification, though it is of high value in the clearing up of our conceptions of the essential contrasted with the accidental, the relation of genus, differentia and definition and so forth, is of more significance in connexion with abstract sciences, especially mathematics, than for the physical sciences.