Free Necessity by Jo Walton

Seventy-Third Year of the City, a human spaceship arrived in our solar system and began broadcasting to our planet. Communication was established, and the protocols were put into place which had been long prepared for such an eventuality.
    We always knew that we would come into contact with Earth sooner or later. Zeus had promised Arete posterity, and how else might it be achieved? Besides, Porphyry had prophesied that such a thing would happen. We did not, however, know in advance exactly when it would occur. Nor could we have predicted what would follow from this recontact.
    VI. On the Nature of the Gods
    After Zeus moved the Cities to the planet Plato, which is considerably less convenient for some things than Greece, Pytheas and his children, with Maia, returned to us from Olympos. Pytheas could no longer keep it secret in the City that he was Apollo incarnate. He would answer some questions about the universe, but not others. “I don’t know everything, I certainly don’t know all the answers,” he said to me. “And sometimes I don’t answer because it’s better for people not to know.”
    â€œKnowledge is good. How can ignorance be better?” I inscribed on a nearby marble plinth.
    â€œCertainty closes many doors,” he replied. “It leads to dogmatism. Souls accept what they know and stop striving upwards.”
    â€œEven among philosophers?” I asked.
    He paused, and his eyes lost focus for a moment. “I don’t know,” he said. “True philosophers, who believe the unexamined life is not worth living, are usually very few in a population. Even here, a lot of people want to receive wisdom rather than work on it, even among the Golds. And what we can explain is only an approximation, an allegory, not Truth.”
    In his later years, Pytheas used to joke about having the words Plato Was Wrong inscribed above the door of Thessaly, because people so often asked him questions based on Plato’s incorrect assumptions about the universe.
    I shall now record a conversation I had with Pytheas in the garden of Thessaly, the day we rooted out the old lemon tree, which had not survived the harsher climate of our new planet. It was three years after the Relocation, and none of the new Workers had yet achieved self-consciousness, nor had we yet encountered any aliens. It was early spring, shortly after we had built the first speaking-boxes, and I was still excited to use my new ability to speak aloud. “Plato says the gods wouldn’t change shape because it would be changing to something less perfect,” I said. My voice buzzed as I spoke, as it always did until we bought better speaking-boxes from the Saeli years later.
    â€œPerfect for what?” Pytheas asked. “A dolphin is much more suited to swimming than a human form. I never swam as a human until I came to the City—and I’ll probably never do it again, the sea here is freezing.”
    â€œIt has never fallen below freezing,” I pointed out. “We don’t have sea-ice.” It was spring, and air temperatures were above freezing now, except sometimes at night.
    â€œMetaphorically freezing, even in summer,” Pytheas said, rolling his eyes.
    â€œWas that pedantic?”
    â€œYes, it was pedantic, but never mind. I was simply complaining about the cold here, the way everyone does.”
    I began to stack the wood against the wall, lining up the pieces. “I can measure temperature, but I don’t feel it.”
    â€œWhen I’m a god, I can choose how much I feel it.”
    â€œThat’s closer to perfection,” I pointed out.
    â€œI never said it wasn’t. Plato’s doing his thing there where he assumes there’s only one good.” He was bent over sweeping up the wood chips, and he hesitated, looking at me where I was stacking the logs, which would make useful material for so many things. “We have our perfect selves, if you