How is the path of thought to progress in its self-education? Hegel introduces such means through the idea of a determinate nothingness.
The skeptic, as for example the epistemological skeptic he has been discussing, takes his negative orientation to knowledge to have an absolute conclusion. On this view, when we call into question the phenomenon, our calling into question leaves an absolute nothingness--there is nothing to the phenomenon, now called into question, on which we could hang any epistemic claims. Precisely because phenomenon are taken, in themselves, to be an absolute nothing, the epistemologist must engage in the preemptive halt and seek first a rule in its own operations by which things may be taken as having content.
But this is not an accurate account of what goes on, Hegel says. He wants us to recognize these sorts of negations as what they are rather than considering their conclusions to be absolute, i.e. dogmatically stated. The epistemological skepticism has taken a certain orientation to being in which it has negated its content, but this orientation and negation does not produce an absolute nothingness, but rather a quite determinate conception of thought and being. The nothingness produced by such skepticism is then, Hegel says, a determinate nothingness--it has a content. Far from demanding thought halt in its tracks, then, such a nothingness indeed provides the means forward, for thought must reflect on this content, and in so doing finds itself in the new situation that this content depicts.
The skeptic negation is not denied in favor of an immediate intuition of being, but rather is subsumed as a moment in the soul's self-education, a moment with content and providing a means forward, and this means forward presenting the nature of our mediate intuition of being.