In 1752, more than a hundred years before the discovery of Mars' moons - Phobos and Deimos - the famous French thinker, Voltaire, mentioned in his tale "Micromegas" that around Mars there are two moons which "escape the eyes of Earth's astronomers".

Indeed, the moons escaped until 1877, until the most powerful telescope appeared. But if astronomers didn't know about it, then where did the philosopher find out?