Of all obstacles to understanding the foundations of physics, it is difficult to point to one more challenging than the question, “How Come the Quantum?” unless it be the twin question, “How Come Existence?” Stuck, but studying every available clue, (Box 1), from the papers of Bohr, Einstein, Planck and Schrödinger to the thoughts of the presocratic philosophers, (Box 2), I remember one of the great messages I have received from sixtyfive years of research: Why does a university have students? To teach the professsors! Not least in convincing me of that lesson is the wealth of learning that I owe to Charles W. Misner, graduate student at Princeton University from 1953 to 1957.

Already from the time Misner dropped into my office to talk about a conceivable thesis topic, I gained a vivid impression of what it was to see his active mind at work comparing researchable issues in elementary particle physics and in general relativity. “What is timely and tractable?” That is the proper criterion of choice, according to John R. Pierce, that great guide of productive research at Bell Telephone Laboratories and animating spirit of the travelling-wave tube and the Tel Star satellite.

Charles Misner, so far as I could see, used the same criterion in making his decision. It led to a Ph.D. thesis and a 1957 paper in the Reviews of Modern Physics, entitled “Feynman quantization of general relativity,” forerunner to the great and influential 1962 paper of R. Arnowitt, S. Deser and Misner on the “Dynamics of General Relativity.”