Thus far, studies in the history of twentieth-century physics have focused on developments until 1927. Testimony to the vigor of this work is the rich secondary literature on the special and general theories of relativity and on quantum mechanics into its interpretive phase.

Historical research into the genesis of quantum electrodynamics is only just beginning. There are good reasons for this hiatus, chief among them being the complexity of the subject matter. The goal of this book is to provide a properly introduced corpus of primary source materials in English to physics researchers and students whose day-to-day activities preclude literature searches, and to historians and philosophers of science interested in the genesis of a theory that has been on the cutting edge of physics ever since P. A. M. Dirac's quantization of the radiation field in 1927: quantum electrodynamics.

Like the papers chosen for this volume, the Frame-setting essay emphasizes conceptual transformations during 1927–38, which carried physicists to the threshold of renormalization theory. For the most part the leaders in fundamental developments in quantum electrodynamics were the same physicists whose focus on conceptual matters led to the fully interpreted quantum mechanics in 1927: Niels Bohr, P. A. M. Dirac, Werner Heisenberg and Wolfgang Pauli. This constitutes the subject matter of Chapter 1 of the Frame-setting essay. Throughout Chapter 1 runs the metaphor of the harmonic oscillator representation for a bound electron, which found its highest development in the second-quantization methods discussed in Chapter 2.