„Die Erde als die einzige bevölkerte Welt im unendlichen All anzusehen, ist ebenso absurd wie die Behauptung, auf einem ganzen mit Hirse besäten Feld würde nur ein einziges Korn wachsen.“

nach Ernst Sandvoss: Vom Homo sapiens zum Homo spaciens, in: Weltbilder der Philosophie - Aufsätze und Vorträge. Hamburg 2007, S. 150 books.google http://books.google.de/books?id=bu2SvITE3QsC&pg=PT150&dq=metrodoros
("Μητρόδωρος δέ φησιν ἄτοπον εἶναι ἐν μεγάλῳ πεδίῳ ἕνα στάχυν γενηθῆναι καὶ ἕνα κόσμον ἐν τῷ ἀπείρῳ. ὅτι δ᾽ ἄπειρος κατὰ τὸ πλῆθος, δῆλον ἐκ τοῦ ἄπειρα τὰ αἴτια εἶναι: εἰ γὰρ ὁ μὲν κόσμος πεπερασμένος, ὅτι δ᾽ αἴτια πάντα ἄπειρα, ἐξ ὧν ὅδε ὁ κόσμος γέγονεν, ἀνάγκη ἀπείρους εἶναι. ὅπου γὰρ τὰ πάντα αἴτια, ἐκεῖ καὶ τὰ ἀποτελέσματα αἴτια δ᾽ ἤτοι αἱ ἄτομοι ἢ τὰ στοιχεῖα." - Pseudo-Plutarch, Placita Philosophorum, nach Plutarch: Moralia, Gregorius N. Bernardakis ed., Leipzig Teubner 1893, 5. Auflage. Buch I Kapitel 5 perseus.tufts.edu http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A2008.01.0403%3Abook%3D1%3Achapter%3D5
"To Metrodorus it seems absurd, that in a large field one only stalk should grow, and in an infinite space one only world exist; and that this universe is infinite is manifest by this, that there are causes infinite. Now if this world were finite and the causes which produced it infinite, it is necessary that the worlds likewise be infinite; for where all causes do concur, there the effects also must appear, let the causes be what they will, either atoms or elements." - Plutarch's Morals. Translated from the Greek by several hands. Corrected and revised by. William W. Goodwin, PH. D. Boston. Little, Brown, and Company. Cambridge. Press of John Wilson and son. 1874. 3. perseus.tufts.edu http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A2008.01.0404%3Abook%3D1%3Achapter%3D5)