The catalytic event for Rialto's Ascensionist faith was the Descension, or the arrival of the Ark. In the past, Trivuria was thought to be a closed system: no matter in, no matter out. The only substance allowed to pass through was the cosmic fluid that permeated the entire universe. But the arrival of the Ark changed everything. For the first time, an alien entity would penetrate the celestial sphere.

  On the day of the Descension, nothing seemed amiss in the city-state of Ostia at first. Gentle gusts of wind blew over its sands as usual. The cosmic ocean lapped up against its shores. Billowing clouds glistened in the sun. But in the afternoon, people began to notice a subtle dimming in the sky. Shadows were becoming strange, their edges now fuzzy and ill-defined. An odd chill hung in the air. Finally, astronomers noticed a strange object overhead, one that was clearly matching Trivuria’s trajectory through the universe.

  This descending object, which was christened the Ark, seeming to be dead-set on Ostia's city center. It soon became clear that the Ark was accelerating. And then it was just 500 meters overhead, casting a shadow over the entire city. Soon, all of Ostia and its surrounding areas were evacuated. It seemed like the end of the world.

  But just 50 meters away from violent contact, the Ark came to a halt. And then… silence.

  For a while, no one dared to approach the Ark. It seemed to be a sphere not unlike Trivuria itself, only city-sized rather than planetary. Its underside had a prominent circular opening, through which light was visibly emanating from within. Still, despite the built-in entrance, the Ark was far from inviting. The Ostians made some primitive attempts to communicate: hand signs, loud noises, thrown objects, but none of them provoked any kind of recognizable response.

  Curiosity eventually got the better of the Ostians, who felt safe enough to return to their city after a few days. The city began work on a staged "Arktower" to reach the Ark by the end of the year. It was to be a huge undertaking, with half the population pitching in on the project. Laborers from abroad joined in out of sheer curiosity, seeking to earn their place in the first meeting with an alien civilization.

  It wasn't long before other nations caught wind of these developments. Since the matter was clearly of global interest, they decided that the matter could not be left up to Ostia alone. They persuaded Ostia to relinquish sovereignty over the Ark in exchange for a generous permanent subsidy and the right to levy a toll on all travel in and out of the region. Of course, Ostia didn't have much choice as a minor power. But they would receive a vote on the newly-formed council designed to arbitrate Ark matters, which was to be called the Arkanum.

  Once the Arkanum took control over the project, it expanded massively in scope. The nations of the Arkanum didn't want to be caught off guard by an alien army waiting above, so they treated it as a full military invasion. Ostia's once proud Arktower became a city-spanning structure called the Arkbridge, designed to facilitate the passage of a legion of fully-armed Trivurians. A base of operations was to be built just below the mouth of the Ark, from which an expedition could begin.

  Stolen novel; please report.

  When the Arkbridge finally reached the Ark, the Trivurians received the news with apprehension. For their entire lives, Trivurians had assumed that they were the only beings in the entire universe. Diplomats and soldiers alike braced themselves for what would surely be a fraught cultural exchange with existential implications, perhaps even war.

  The Trivurians were delighted to find nothing less than a metropolis inside, which was wrapped around the curved inner wall of the Ark such that all of the buildings inside pointed towards the center. At that center was the powerful light source visible from the Ark's mouth, so brilliant that it was difficult to gaze upon. It was a disorienting sight.

  But much to their dismay, the Ark seemed to be deserted. The city inside was surprisingly devoid of media, technology, and anything that suggested the existence of people. There was no food, no trash, no mess, and the few artifacts that were present seemed intentionally left there for them to find, as a sort of pedagogical exercise.

  The first building they entered featured detailed paintings of humans in a variety of settings. Some of the paintings were similar to the fashionable art of Trivuria at the time, while others were rather vulgar and depicted human anatomy in graphic detail. Most took these paintings as an assurance that the original occupants of the place were human. Skeptics wondered if it was more of an assurance that the original occupants understood humans. Or perhaps this was the wrong question— were there even any original occupants at all?

  Other buildings were more difficult to decipher. Some contained diagrams of strange contraptions, which seemed designed to unleash a violent energy into the world. Others were more unsettling, like the ones depicting unsettlingly large birds of prey. Each building seemed to be replicated by the buildings to its left and right, forming "rings" of identical buildings at each level of elevation.

  The Arkanum concluded that the original inhabitants of the Ark were clearly intelligent, and they were perhaps even actual humans like the Trivurians. Still, there seemed to be no one left from this strange civilization to shed light on what they had left behind.

  The most interesting building inside the Ark by far was its singular massive cathedral, located directly above the Ark's mouth at the far side of the sphere. It had a bizarre skeletal structure, with ostentatious wooden support trusses announcing themselves without shame. But its geographic centrality alone suggested the significance of the place, not to mention its status as the only building without a copy.

  After heated discussion, the Arkanum decided to sanction an expedition into this numinous holy place. Three men, handpicked by the Arkanum leadership, were sent inside to lead an expedition into the nave.

  The nave was a cavernous space, adorned with strange murals that suggested unknown rhythms of the universe. Unsurprisingly, at the front of the nave was an altar. Surprisingly, atop the altar was a human child.

  One of the men rushed to the altar in alarm, fearing that the child might be in danger of starving, or worse. But as soon as he touched the altar, he fell to his knees and began to convulse, frothing at the mouth. Alarmed, the two other men rushed to his side. But upon making contact, they too collapsed into convulsions. The rest of the horrified expedition dared not approach them, nor the child.

  When the three men regained consciousness after several hours, they each independently reported seeing the same terrible vision.

  A vision that foretold the death of their world.