Complex sentence: Between 1619 and 1621 he was a teacher at the college of Rouen but was almost expelled from the Society because he contracted tuberculosis in 1620--an illness which prevented both studying and teaching for the traditional periods.
Split into simpler sentences: Between 1619 and 1621, he was a teacher at the college of Rouen. He was nearly expelled from the Society because he contracted tuberculosis in 1620--an illness which prevented both studying and teaching for the traditional periods.