This small book contains lectures from the Haskell Readings series that I gave at the University of Chicago in the fall of 1956 on the general topic of “Patterns of Initiation.” Before sending the text to the publisher, I added an introduction, some notes and bibliographical apparatus, but retained the style of an oral presentation. In the form in which the book was conceived, it is addressed to any non-specialist reader interested in the spiritual history of mankind.