During the almost 40 years that I have been following it, there has been an amazing (to me, at any rate) change in the tenor of the discussion about the relation between quantum field theory and general relativity. In 1957, I started graduate studies at Stevens Institute of Technology, then a world center of relativity research: there were actually three people there who worked on such problems! I soon started attending the famous informal Stevens relativity meetings, getting to know many of the leading figures in the field, and meeting most of the others at the 1959 Royaumont GRG meeting.

This was a time of high tension, of struggle between two rival imperialisms, one clearly much stronger than the other. I am referring, of course, to the dominant quantum field theory paradigm, which was stubbornly resisted by the much weaker unified field theory program. I call these two programs imperialisms because each had a universalist ideology used to justify an annexationist policy. Einstein's unified field program aimed to annex quantum phenomena by means of some generally covariant extension of general relativity that would include electromagnetism, somehow miraculously bypassing quantum mechanics. The structure of matter and radiation, including all quantum effects, would result from finding non-singular solutions to the right set of non-linear field equations. In spite of repeated failures over 30-40 years, Einstein persisted in working toward this goal, though not without increasing doubts, particularly towards the end of his life.