for no two terms can differ unless they both are, i.e. fall within the same universe. Further, each difference implies a basis of its own, and each sort of difference a special sort of basis. So intimate is the connexion between the difference of two terms and their unity, that it may be said that they differ precisely in respect of what they are or have in common, and vice versa. Thus red and blue differ as colours, i.e. in respect of, and in condition of, their being both colours, and the notes of a scale or a melody differ just because they are related to and within the self-same whole. This coexistence within the same area enters into the nature, of each: to differ is only possible upon a basis of agreement; to be different, two terms must have not only something in common, but precisely that in respect of which they differ. Nor is it possible to assert—except verbally—their difference without recognizing their 'identity'.
The deeper their difference (if we may speak of depth, in distinction from width, of difference), i.e. the more profoundly the difference enters into their several natures, the more intimate is the bond of union between them and the more penetratingly is the nature of each coloured by the fact of their joint membership of the whole, and vice versa. How far-reaching is the difference between two lovers of one mistress! And it is so because they are so thoroughly at one. Philosophers have made themselves a byword by the dissidence of their dissent, and yet where can we find as among them so extensive a mutual understanding? Differences can only exist—or at any rate can only live and thrive—on a basis of identity, as identity can only live and thrive on differences. ἐκ τῶν διαφερόντων καλλίστη ἁρμονία. What alone is real is the system which permits and requires both. Therefore it is that
