Plutarch Quote

Alexander wept when he heard from Anaxarchus that there was an infinite number of worlds; and his friends asking him if any accident had befallen him, he returns this answer: "Do you not think it a matter worthy of lamentation that when there is such a vast multitude of them, we have not yet conquered one?"

On the Tranquillity of the Mind - Bartlett's Familiar Quotations, 10th ed. (1919)