In modern physical science the opposition, first observed to exist in magnetism as polarity, has come to be regarded as a universal law pervading the whole of nature. This would be a real scientific advance, if care were at the same time taken not to let mere variety revert without explanation, as a valid category, side by side with opposition. Thus at one time the colours are regarded as in polar opposition to one another, and called complementary colours: at another time they are looked at in their indifferent and merely quantitative difference of red, yellow, green, &c. (2) Instead of speaking by the maxim of Excluded Middle (which is the maxim of abstract understanding) we should rather say: Everything is opposite. Neither in heaven nor in earth, neither in the world of mind nor of nature, is there anywhere such an abstract 'Either--or' as the understanding maintains. Whatever exists is concrete, with difference and opposition in itself. The finitude of things will then lie in the want of correspondence between their immediate being, and what they essentially are. Thus, in inorganic nature, the acid is implicitly at the same time the base: in other words, its only being consists in its relation to its other. Hence also the acid is not something that persists quietly in the contrast: it is always in effort to realise what it potentially is. Contradiction is the very moving principle of the world: and it is ridiculous to say that contradiction is unthinkable. The only thing correct in that statement is that contradiction is not the end of the matter, but cancels itself. But contradiction, when cancelled, does not leave abstract identity; for that is itself only one side of the contrariety. The proximate result of opposition (when realised as contradiction) is the Ground, which contains identity as well as difference superseded and deposed to elements in the completer notion. 120.] Contrariety then has two forms. The Positive is the aforesaid various (different) which is understood to be independent, and yet at the same not to be unaffected by its relation to its other. The Negative is to be, no less independently, negative self-relating, self-subsistent, and yet at the same time as Negative must on every point have this its self-relation, _i.e._ its Positive, only in the other. Both Positive and Negative are therefore explicit contradiction; both are potentially the same. Both are so actually also; since either is the abrogation of the other and of itself. Thus they fall to the Ground.--Or as is plain, the essential difference, as a difference, is only the difference of it from itself, and thus contains the identical: so that to essential and actual difference there belongs itself as well as identity. As self-relating difference it is likewise virtually enunciated as the self-identical. And the opposite is in general that which includes the one and its other, itself and its opposite. The immanence of essence thus defined is the Ground.