Interview discusses, not in chronological order: early home life and schooling; undergraduate at Leiden, influence of Paul Ehrenfest, Jan H. Oort, Jacobus C. Kapteyn, Gerard Kuiper, Antonie Pannekoek, Ejnar Hertzsprung. Recollections of work of Georg Uhlenbeck and Samuel Goudsmit. Assistant to Peter van Rhijn at Groningen ca. 1928, work on various stellar and galactic topics. Move to Harvard, 1929, and atmosphere there under Harlow Shapley. Marriage to Priscilla Fairfield Bok; her contacts with William W. Campbell.