Is all that we see or seem /But a dream within a dream?

And the raven, never flitting, still is sitting, still is sitting On the pallid bust of Pallas just above my chamber door; And his eyes have all the seeming of a demon's that is dreaming, And the lamp-light o'er him streaming throws his shadow on the floor; And my soul from out that shadow that lies floating on the floor Shall be lifted -- nevermore.
Edgar Allan Poe - The Raven