In Act I Scene 4 Romeo says that he dreamt a dream but gives us no details of it. What clue does give toward the end scene as to its ominous nature?

Romeo says, "My mind misgives some consequence yet hanging in the stars shall bitterly begin his fearful date / With this night's revels, and expire the term / Of a despisèd life closed in my breast / By some unwilling hand."

This suggests that Romeo had a premonition of his own death, which foreshadows the tragic events that will occur later in the play.