By the end of Poul Anderson's "The Communicators" (Dialogue With Darkness, New York, 1985), we have a probable, an almost certain, answer to the question:
why does human mentality seem to be unique at least within the local interstellar communication network?
Subsidiary questions:
Why do extra-Solar intelligences not seem to understand requests for biological data, including pictures of life forms?
Why do those intelligences send mathematical and technical information but nothing artistic or psychological?
How is it that a spaceship is now en route to the Solar System at one sixth of C although, at that speed, radiation would destroy any organisms aboard?
Probable answer: in those planetary systems, artificial intelligence has replaced organic intelligence.
So is the approaching spaceship a berserker, programmed to destroy all organic life? That is not the story's implication although it is an outside possibility. There are fifty eight years until ETA, so that is fifty eight years for humanity to learn vigilance and unity.
As in the preceding story, "Dialogue," Anderson applies historical knowledge to futuristic fiction. Colonel Duna of the Domination of Baikal, an imperial power, appears at first to be the villain of the piece but we must reassess him before the end. He and his kind study history in order not to repeat it. He thinks that the Roman Empire stopped expanding too soon whereas the British Empire spread itself too thin. He hopes that Baikul will endure and learn - including from the aliens when they arrive.
Living millennia in our future, Duna and his compatriots have correspondingly more history to learn from: there has been a Great Asia (which featured in the story, "SOS"), an Empire of the Americas, a Midafrican civil war and a militant Martian religion. Duna ends the story with the perceptive remark that, without eternally returning night, there can be no sunrises.
