The people of Sunfall do not live on the surface of a world. They live on the skin of one. Beneath the stone, beneath the deep-root systems of the oldest forests, beneath the sediment floors of the oceans, the world does not continue as geology. It continues as something else — a substrate that precedes matter, a stratum of compressed intention older than the physics that govern the upper world, in which the distinction between thought and substance has never been established. The scholars who have come closest to naming it call it the Undermeridian, a term that is simultaneously geographical and philosophical: the point below the highest point, the inverse zenith, the nadir so deep it curves back into meaning. Most people who learn the word stop using it after a while. It feels too much like an invitation.
The cosmology of Sunfall is not theological in any comfortable sense. There are no gods in the tradition that the word implies — no personalities of divine scale engaged in the governance of mortal affairs, no pantheon negotiating the seasons, no creator who remembers making the world and takes an interest in its continuation. What exists instead are the Abidants: entities of such foundational age and mass that the word entity strains under their weight. The Abidants did not make Sunfall. They preceded it. The world formed around them the way stone forms around an intrusion — the intrusion was not interested in the stone, did not shape the stone deliberately, and is not aware of the stone in any way that the stone would recognize as awareness. The Abidants are not sleeping, though the literature of every civilization that has glimpsed their existence reaches instinctively for that metaphor, because the alternative — that they are fully present and fully conscious and have simply never found anything in the human world worth the motion of attention — is a conclusion most minds refuse to complete.
The sun itself occupies a cosmological position that no philosopher of Sunfall has ever satisfactorily resolved. It is real in the empirical sense — it rises, it moves, it produces heat and light. But its rising has slowed. Not measurably, not in any way that an astronomer could chart in a single lifetime, but across generations the records are unambiguous: the sun reaches a lower point in its arc than it once did. The meridian — the highest point of the solar transit, the zenith of noon — has been sinking for three hundred years. Not dramatically. Not catastrophically. Just persistently, incrementally, in the way that a very slow tide announces itself not in any single wave but in the gradual discovery that the shoreline is not where it was. The philosophers who study this phenomenon are called Meridianists, and they are not optimistic people.
Beyond the physical sun, Sunfall exists within a cosmological field that its most unsettled thinkers describe as the Lattice — an invisible structural web of resonance connecting the world to things outside it. The Lattice is not a network of meaning or divine intention. It is closer to a frequency, a vibration at a scale so immense that the human sensorium cannot detect it directly, only its effects: the slow warping of stone near certain ruins, the way certain tones played on certain instruments produce not sound but an atmosphere of dread that takes hours to dissipate, the recurring geometric patterns — spirals, radial lattices, asymmetric branching forms — that appear independently in the art of every culture on Sunfall that has ever existed, including cultures that could not have communicated with one another, including cultures that predate human civilization on this world by eons. The Lattice is not sending messages. It is not communicating. It is simply present, as gravity is present, and its presence does what gravity does: it bends everything in its vicinity toward itself, slowly, without intention, without mercy, without end.