Complex sentence: After teaching for about twenty years in Chartres, he lectured on dialectics and theology in Paris (from 1137), and in 1141 returned to Poitiers, being elected bishop in the following year.
Split into simpler sentences: After teaching for about twenty years in Chartres, he lectured on dialectics and theology in Paris (from 1137). In 1141 he returned to Poitiers, being elected bishop in the following year.