As the proceedings of a symposium in honor of Victor Weisskopf at MIT, this volume contains papers by leaders of physics at the time, including M Delbrück, M Gell-Mann, H Bethe, T D Lee, B R Mottelson, W K H Panofsky, E Purcell, J Schwinger, S M Ulam, and others. Some papers address problems in the philosophy of physics, and physics and society, that are timeless in nature. But the symposium had a historical significance, in that it took place at a historic juncture of particle physics — the emergence of the Standard Model owing to experiments that point to the existence of quarks. Some of the papers reflect both the pre-quark and post-quark points of view. For these reasons, these proceedings merit reissue and reexamination.