Virgil, Aeneid 7.312
While we’re on the subject of dreams, here’s a line quoted by Freud in The Interpretation of Dreams. Juno has been frustrated in her efforts to end the building work on Rome, and utters this grimly chilling line, which Freud applies to suppressed thoughts that find ‘methods and means of forcing [their] way into consciousness’.
flectere si nequeo superos, Acheronta movebo.
If I cannot bring round the gods above, I will move the Underworld.