  Cornelis ("Kees") de Jager, co-founder of "Solar Physics", passed away in
2021. He was an exemplary human being, a great scientist, and had large impact
on our field. In this tribute we first briefly summarize his life and career
and then describe some of his solar activities, from his PhD thesis on the
hydrogen lines in 1952 to the book on cycle-climate relations completed in
2020.
