Kitap 10
7
E.g., if white and black are contraries, and the one is a penetrativeThis is Plato’s definition. Cf. Plat. Tim. 67d, e. and the other a compressive color, these differentiae, penetrative and compressive, are prior, and so are opposed to each other in a prior sense.
8
But it is the species which have contrary differentiae that are more truly contraries; the other, i.e. intermediate, species will consist of genus and differentiae. E.g., all colors which are intermediate between white and black should be described by their genus (i.e. color) and by certain differentiae.
9
But these differentiae will not be the primary contraries; otherwise every thing will be either white or black. Therefore they will be different from the primary contraries. Therefore they will be intermediate between them, and the primary differentiae will be the penetrative and the compressive. Thus we must first investigate the contraries which are not contained in a genus, and discover of what their intermediates are composed.
