Pieter Zeeman (1866–1943) came into my professional life, so to speak, when I totally unexpectedly discovered his papers in the fall of 1989. They were still in the house in Amsterdam he had lived in most of his professional life and came to light after the death of his son Jan. They were in total disarray, but after a major rearrangement operation they are now housed in the Noord-Hollands Archief in Haarlem, fully accessible to anyone interested. The papers are amazingly complete and cover his professional career in full, in correspondence, scientific notes, lecture notes and other documents. Unfortunately I have not had enough time to fully explore the archive; I have written a detailed biographical article (in Dutch) on Zeeman, though, as well as two papers on the discovery of the Zeeman effect and its aftermath, one in Dutch and one in English. It is still on my agenda to study the history of the Zeeman effect in more detail.