Angels Fear to Tread , but often referred to by him as Angels Fear . In June 1980 I came out to Esalen, where he was living, having heard that his health was again deteriorating, and he proposed that we collaborate on the new book, this time as coauthors. He died on July 4, without having had the opportunity to begin work, and after his death I set the manuscript aside while I followed through on other commitments, including the writing of With a Daughter’s Eye (Morrow, 1984), which was already under way. Now at last, working with the stack of manuscript Gregory left at his death – miscellaneous, unintegrated, and incomplete – I have tried to make of it the collaboration he intended. It has not seemed to me urgent to rush this work forward. Indeed, I have been concerned on my own part to respect the warning buried in Gregory‘s title: not, as a fool, to rush in. The real synthesis of Gregory‘s wo rk is in Mind and Nature , the first of his books composed to [[p_002] communicate with the nonspecialist reader. Steps to an Ecology of Mind [Chandler, 1972, and Ballantine, 1975] had brought together the best of Gregory‘s articles and scientific papers, written for a variety of specialist audiences and published in a multiplicity of contexts, and in the process Gregory became fully aware of the potential for integration. The appearance of Steps also demonstrated the existence of an audience eager to approa ch Gregory‘s work as a way of thinking, regardless of the historically shifting contexts in which it had first been formulated, and this moved him along to a new synthesis and a new effort of communication. Where Angels Fear to Tread was to be different. He had become aware gradually that the unity of nature he had affirmed in Mind and Nature might only be comprehensible through the kind of metaphors familiar from religion; that, in fact, he was approaching that integrative dimension of experience he called the sacred . This was a matter he approached with great trepidation, partly because he had been raised in a dogmatically atheistic household and partly because he saw the potential in religion for manipulation, obscurantism, and division. The mere use of the word religion is likely to trigger reflexive misunderstanding. The title of the book therefore expresses, among other things, his hesitation and his sense of addressing new questions, questions that follow from and depend upon his previous work but require a different kind of wisdom, a different kind of courage. I feel the same trepidation. This work is a testament, but one that passes on a task not to me only by to all those prepared to wrestle with such questions.