The role of Professor Dr Gerhard Soff (deceased on 10 December 2004) in the creation and development of the theory of quantum electrodynamics (QED) of strongly bound electrons in quasi-molecules, highly charged ions and atoms is highlighted. The most important achievements by Professor Soff in this area of research are revisited and commented. Emphasis is placed on a summary of the results of his long-term research activity devoted to bound state QED.