Complex sentence: An economist, Diederichs obtained a doctorate from the University of Leyden, and during the 1930s and 1940s he became a prominent figure in Afrikaner nationalist circles.
Split into simpler sentences: An economist, Diederichs obtained a doctorate from the University of Leyden. During the 1930s and 1940s he became a prominent figure in Afrikaner nationalist circles.