Hegel On Dialectic I

"That which enables the Notion to advance itself is the already mentioned negative which it possesses within itself; it is this which constitutes the genuine dialectical moment. Dialectic in this way acquires an entirely different significance from what it had when it was considered as a separate part of Logic and when its aim and standpoint were, one may say, completely misunderstood. Even the Platonic dialectic, in the Parmenides itself and elsewhere even more directly, on the one hand, aims only at abolishing and refuting assertions through themselves and on the other hand, has for its result simply nothingness.

Dialectic is commonly regarded as an external, negative activity which does not pertain to the subject matter itself, having its ground in mere conceit as a subjective itch for unsettling and destroying what is fixed and substantial, or at least having for its result nothing but the worthlessness of the object dialectically considered." - Hegel. Science of Logic I.67.