Originally published in 1933, Conversion is a seminal study of the psychology and circumstances of conversion from about 500 B.C.E. to about 400 A.D. A.D. Nock not only discusses early Christianity and its converts, but also examines non-Christian religions and philosophy, the means by which they attracted adherents, and the factors influencing and limiting their success. Christianity succeeded, he argues, in part because it acquired and adapted those parts of other philosophies and religions that had a popular appeal.