ὁ Ἡράκλειτός φησι τοῖς ἐγρηγορόσιν ἕνα καὶ κοινὸν κόσμον εἶναι, τῶν δὲ κοιμωμένων ἕκαστον εἰς ἴδιον ἀποστρέφεσθαι
Heraclitus says that to the waking there is one world in common, but sleepers dwell each one in a several world.
Plutarch, De superstitione, 166c
Here we are all by day; by night w'are hurled
By dreams, each one into a sev'rall world.
Robert Herrick (1591-1674)