March 9, 1972: Natural and Supernatural (letter)
August 18, 1966: Large Questions (letter)
February 17, 1966: Dangerous Animal (letter)
February 25, 1965: Where Do We Go From Here?
Continuities in Cultural Evolution by Margaret Mead
The Future of Man by Pierre Teilhard de Chardin
September 10, 1964: A Dark Side of the Renaissance
Giordano Bruno and the Hermetic Tradition by Frances A. Yates