For a fascinating read on two of the 20th century’s dominant intellectuals, I recommend The Question of God, by Dr. Armand Nicholi. The theme is a theoretical debate between two giants, Sigmund Freud and C. S. Lewis, who never actually met, but whose lives surprisingly paralleled and whose thought, in the end, anchored opposite poles of worldview and the meaning and purpose of life. It would be difficult to finish this book without an introspective analysis of your own purpose in life and contemplation of its two recurring questions–what should we believe? and how should we live? It is amazing how the opposing worldviews of these men continue to define many of our current philosophical and psychological conflicts.