I've used this Arthur C. Clarke quote before, but I came across it again while working on an article for Cosmos, and it's worth another look. The elements of technological meliorism and posthuman vision in Clarke's work are nicely blended here, in a passage from Profiles of the Future .
Writing, though he was, decades before "transhumanism" was more than a stray word coined by Julian Huxley, Clarke draws a clear transhumanist implication, one that needs no glossing from me. He acknowledges a criticism by Lewis Mumford of the prospect of space colonisation, then responds with a memorable image of his own:
But when [Mumford] wrote: "No one can pretend ... that existence on a space satellite or on the barren face of the Moon would bear any resemblance to human life", he may well be expressing a truth he had not intended. "Existence on dry land", the more conservative fish may have said to their amphibious relatives, a billion years ago, "will bear no resemblance to piscatorial life. We will stay where we are."
They did. They are still fish.