This unhappy consciousness, divided and at variance within itself, must, because this contradiction of its essential nature is felt to be a single consciousness, always have in the one consciousness the other also; and thus must be straightway driven out of each in turn, when it thinks it has therein attained to the victory and rest of unity. Its true return into itself, or reconciliation with itself, will, however, display the notion of mind endowed with a life and existence of its own, because it implicitly involves the fact that, while being an undivided consciousness, it is a double-consciousness. It is itself the gazing of one self-consciousness into another, and itself is both, and the unity of both is also its own essence; but objectively and consciously it is not yet this essence itself — is not yet the unity of both.
The terminology here is always alert to the possibility of undoing this internal separation--'return or reconciliation' as Hegel puts it--as if the severance is no differend, but that between two rational agents who have, unaccountably, fallen out. But this isn't our experience, of course. It's the unified consciousness that is the unhappy one: the monomaniac, the man or woman of fundamentalist faith and Dalek-eyed certainty, the obsessive. Their consciousness is unhappy; they're just too myopic to realise it. Or perhaps a better way of putting it would be that, like any distracting agent, Dalek-eyed certainty obscures one's own unhappiness from oneself.
Of course, an understanding not of the doubleness but the quadrupleness of our consciousnesses is the route to a healthier psyche. Hegel wants to suggest this latter case, by reserving a properly dialectical consciousness to happiness ('an undivided yet double-consciousness')--a weirdly non-violent version of the dialectic, surely ... 'the gazing of one self-consciousness into another'. But its precisely the turbulence of that wavefront, the immiscibility of consciousness with consciousness, that determines what subjectivity is. Not gazing, but intervening, invading, interpenetrating. Revolution, not neutral observation. Sex, not voyeurism.