How I understand "horizon"

horizon is a boundary throughout the history of philosophy. But I see not a simple boundary but a confined area, not an empty mediating concept, the concept of the mediation itself, but the area between the abyss and the sky. We mortals have built the sky, that is, we dwell in it, and preserve in it the fourfold. The sky is the realm of "truth", of belief, of "fact", of knowledge. In the sky lies all those things we hold, things that seem to stand fast. But what do they stand on that enables us to hold them and not let them slip through our hands like butter? Reality, some say. The correspondance of assertion to reality, perhaps. But what is reality but another empty concept, an "error" or "vapor" that evaporates with the emergence of the sun. A concept simply created to ground our beliefs, to enable "truth", to allow the arrogant and condescending who cannot bear to lose to be "right". Everything stands on a leap, a leap from the ground over the abyss (where reality disappears as a mirage), to the horizon that grounds the world in identity and non-contradiction; in other words, the horizon is the not-ground grounding the possiblity of holding, creating the ability to stand. The horizon is tautology, as if the "is" were always an equal sign (=) and the "is not" its negation, nevertheless in tautology. Synthetic statements are grounded in analytic statements, if such a difference hasn't collapsed. The horizon, for me, is not only a boundary but the ground of the sky, that grounds as a not-ground the (not-ground of) standing/holding after/above the leap over the abyss from an endless nowhere, from a veritable, beautiful, eternal nothing.