There are many instances of scientific discoveries firing the human imagination and giving rise to literary works, and equally numerous cases of non-scientific beliefs inspiring scientific speculation. This paper touches on these related facets of the essentially interdisciplinary nature of human thought, and focuses on the heliocentric theory as a prime example. The human mind is stirred by new and striking observations rather than by abstract ideas, and what made Copernicanism a popular theory was Galileo’s use of the telescope to show that the Moon has the same features as the Earth. Galileo's discoveries instantly promoted two ancient works of science fiction to the rank of best-sellers. These are Plutarch’s The Face on the Orb of the Moon, which was freshly translated from Greek into Latin by no less distinguished an astronomer than John Kepler, and Lucian’s account of the celestial voyages of Icaromenippus, which was reissued in Greek and in Latin. The likelihood of habitants on other planets was widely discussed by writers who blended science with phantasy, the most famous and successful being Fontenelle who, on beautiful moonlit evenings in a garden between clipped rose hedges, discoursed on the possibility that men and women from the Moon may soon visit us.

Key-words: Science and Literature; Plurality of Worlds; Fontenelle