a very great sin. Neugebauer was amused to point out that the ecclesiastical calendar, considered by church historians to be highly scientific and deeply complex, was actually primitively simple. He then published separately the astronomical chapters of the Book of Enoch (1981) in his own translation and commentary, both rather different from the literature on Enoch by Biblical scholars.

Considerably more complex than either of these was Abu Shaker's “Chronography” (1988), an analytical summary of a chronological and calendrical treatise originally written in Arabic by a thirteenth-century Coptic Jacobite. The treatise probably contains more technical information on ecclesiastical calendars than any other source, including the curious fact that the sequence of 29- and 30-day months is identical in the Jewish and Islamic calendars, showing that the Islamic calendar was in fact derived from the Jewish by suppressing intercalation, in accordance with Muhammad's prohibition. Thus far, I know of no reaction to this discovery. Finally, in Chronography in Ethiopic Sources (1989), he assembled a great deal of chronographical information, that is, intervals between epochs and dates of events, mostly in tabular form.

A few years after he came to this country, Neugebauer began to spend part of his time at the Institute for Advanced Study in Princeton, and from 1950 for the remainder of his life was a long-term member, a continuous association of forty years. Robert Oppenheimer, then director, had told him he would be welcome permanently any time he wished, but he preferred to remain at Brown and visit the Institute periodically. He always found the faculty and visitors at the Institute stimulating; following his retirement from Brown in 1969 and the death of his wife in 1970, he regularly spent several weeks there each fall and spring,