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What was science fiction like in the past? How did ancient people imagine the future?

I don't know if this necessarily fits the mould of a true science fiction book, but Lucian, a second century Syrian Greek composed a story about a trip that he and a group of travelers took to the moon called The True History/Story. In the text, a whirlwind whisks the author and his companions to the moon. The characters arrive in the midst of a war between the kings of the Sun and Moon. You can read for yourself, a parallel Greek/English can be found here: http://www.sacred-texts.com/cla/luc/true/tru01.htm