It's a little known fact that the Ents of Tolkien's The Lord of the Rings were actually inspired by the author's extreme dislike of a scene in Shakespeare's Macbeth. Paul talks the prophecies of Macbeth, their influence on LOTR, and Tolkien's brief use of prophecy himself.

Carpenter, Humphrey, Ed. The Letters of J. R. R. Tolkien. London: Houghton Mifflin, 2000.

Polanski, Roman. Macbeth. UK/USA:  Playboy Productions and and Caliban Films, 1971.

Shakespeare, William. Macbeth. The Riverside Shakespeare. New York: Houghton Mifflin, 1997.   

Tolkien, J. R. R. The Return of the King. London: Harper Collins, 2010.