The First Steps of Quantum Electrodynamics: What Is It That's Being Quantized?

Quantum field theory, and in particular quantum electrodynamics (QED), are milestones in the history of twentieth century physics. Not all interpretative problems presented by them, however, can be said to have been settled once and for all. In this paper the first papers on QED by P. Jordan and P.A.M. Dirac are briefly analysed, with the intent to show that the authors confronted themselves from the beginning with the essential of those problems, that their answers were not unambiguous, and that there are still some open questions concerning the subject matter. The potentiality and up-to-dateness of Dirac's work are particularly emphasised.