Let me summarize some theories concerning the Atheter: they moved on to a higher plain of existence after reaching the apex of material technology, either that or they reached their own singularity and disappeared in a puff of logic having solved their theory of everything; they are still here with us keeping a benevolent eye on younger civilizations, but shifted slightly into another dimension so we cannot now see their vast glittering cities; their technology destroyed them (either their own AIs -if they built them—reached singularity and wiped them out, or they created some unstoppable nano-plague that did the job); or, my personal favourite, having done it all and understanding the emptiness of existence, they deleted their entire civilization, their entire knowledge base, even from their own minds, and started again, as humans. However, despite much speculation and some quite lunatic theorizing, very little is known about the Atheter. There is in fact still much debate about whether they were in fact a race distinct from those other ancient races named, the Jain and Csorians. And argument still abounds concerning what artefacts are attributable to which race, or civilization. But let us be clear on this: actual physical artefacts dating from each period are few. Most of the theorizing is based on such obscure sciences as xenogeneic archaeology, metallo-crustal dispersion and—this one really is obscure—Fifth Gen. Boolean analysis of U-space transitional echoes. It’s all piss and wind really, we’ll probably never know.

— From ‘How it Is’ by Gordon

Thellant turned to gaze at a screen wall. The scene it displayed was taken from cameras high above his present location, and its clarity so good he appeared to be looking through a chainglass window at a pastoral view of patchwork fields, rivers and copses, with only occasional incongruous towers sprouting like vulgar metal plants amid this apparently rural idyll. It was deceptive. Some human, transported to those fields from a past time, would not know that below him lay an arcology housing a billion humans. Fifteen miles straight ahead, a cliff dropped two miles sheer down to the coast, beyond which sea-life breeding pens chequered the shallow ocean extending to the horizon and beyond. That cliff formed one arcology edge. Another edge lay 200 miles behind the present view.