Metrodorus of Chios was a Greek mathematician, grammarian, and atomist philosopher. It isn't known exactly when he lived; it may have been as early as the 3rd century AD or as late as the early 6th century, although the former seems more likely. He compiled a number of mathematical puzzles and witty statements that appear in a later body of work called the Greek Anthology. One of these puzzles is known as Diophantus' riddle. In philosopy, he neatly summed up the pluralist teachings of Epicurus as follows:

To consider the Earth as the only populated world in infinite space is as absurd as to assert that in an entire field of millet, only one grain will grow.