Complex sentence: In 1919 he was ordinary professor of systematic philosophy at Cologne and in 1921 professor of philosophy at Leipzigm though he was a visiting professor in Nanking and Peking during 1922-23.
Split into simpler sentences: In 1919 he was ordinary professor of systematic philosophy at Cologne and in 1921 professor of philosophy at Leipzig. He was a visiting professor in Nanking and Peking during 1922-23.