Crossing between star systems is not a physical impossibility, like exceeding the speed of light, but the eerie silence of the cosmos in the radio band suggests civilizations are as rare as supernovae in our galaxy. If they attain the technology to leave their native planet without simultaneously destroying their own civilization with the same technology, there is nothing to prevent them from thoroughly colonizing their own system as far as the comet cloud at the periphery, but the yawning gap beyond has always stymied them. And humanity is fated to face the same barrier. This is not a judgment on the qualities of mankind or those other races, it is the natural outcome of the mathematical and physical realities that govern our universe. The natural laws that lead to the emergence of life are incompatible with the dream of a far-flung Galactic empire crossed in decadent comfort on the equivalent of ocean liners.

The only successful interstellar travelers are advanced machines capable of repairing and even replacing themselves with raw materials they find in planets, moons, and asteroids, and traveling between systems in time spans on the order not of decades or centuries but of millennia. These machines are immune to the ravages of deep time, and radiation has little effect on them. The creation of such machines are not beyond the capabilities of the seraphim, the alien races that have already colonized their own system, and many were developed as assistants or even as deliberately engineered successors. For those machines capable of replicating themselves the dynamic of descent with variation and natural selection imposes upon them. These are the ophanim, and they are themselves alive in a certain sense. Physical contact between the isolated civilizations of seraphim is mediated solely through the ophanim.

Over billions of years something akin to a theological imperative emerged, an impulse to foster the development of life to the highest level of civilization, that the Continuity might be enriched. But there is a universal consensus to nudge such life they find with minimal interference, lest the diversity the machines cherish with almost religious fervor be diminished. Such has been the case here on Earth as humans proceed toward the status of seraphim. Few suspect the existence of ophanim among us, nor the imperceptible actions they have taken throughout history to kindle our technological civilization. As civilization on Earth progressed the alien machines appeared at times in forms like quite bizarre, like a mobile tree, or a red dragon, or a the interlocked whirling wheels of an orrery . All of these mechanisms in any form are called ophanim, or thrones.