Full Idea
One might indeed be puzzled whether, just as the world about us exists, nothing prevents there being others as well, certainly more than one, though not an unlimited number
Gist of Idea
It seems possible that there exists a limited number of other worlds apart from this one
Source
Aristotle (On the Heavens [c.336 BCE], 274a26)
Book Reference
Aristotle: 'On the Heavens I and II', ed/tr. Leggatt,Stuart [Aris and Phillips 1995], p.71