Nag Hammadi and Manichaean Studies #24.

Research on this book, begun in Paris in 1976, was pursued in Cambridge, Massachusetts. In its original form, the work was submitted in 1978 as a Ph.D. dissertation at Harvard University. It has subsequently undergone many revisions, including some major structural changes, although the main lines of the argument have remained on the whole unaltered. I have also sought to take recent scholarly contributions into account. The manuscript was ready in 1982. The delay in its publication has been due to reasons quite beyond my control; it has not been possible to revise it further.