In the autumn of 1973 I was invited by the Weil Institute of Cincinnati to give a series of lectures there on the subject of Church and State in Byzantium. It was an invitation and an assignment for which I was deeply grateful, not only because of the generous hospitality that I received in Cincinnati, but also because it enabled me to order my thoughts on a fundamental question in Byzantine history.

The six lectures that I gave to the Institute are reproduced here, with a few minor adjustments, needed when the spoken word is transformed into the written word, and with the addition of reference notes. In a short book which covers so wide a subject it would be impractical to attempt to give the original sources for every fact and episode mentioned in the book. I have given the sources for direct quotations; but in general I have referred to modern works in which the interested reader can find further information and bibliographical material on any topic into which he may wish to go further. The references that I give will also indicate how much I am indebted to various scholars whose works have illuminated for me various aspects of the subject.

There is always a problem in the transliteration of proper names from the Greek. A completely consistent system is, I think, impossible without a pedantic introduction of ridiculously unfamiliar forms. I have simply employed in every case what seems to me to be the most familiar form.