Simplify the following text for a Grade 14 native English-speaking person.
Original: He was in charge of the Max Planck Institute in Starnberg ( near Munich ) in 1971 , and worked there until 1983 , two years after the publication of his magnum opus , or great work , The Theory of Communicative Action Habermas then returned to his chair at Frankfurt and became in charge of the Institute for Social Research .
Simplified: He accepted the position of Director of the Max Planck Institute in Starnberg ( near Munich ) in 1971 , and worked there until 1983 , two years after the publication of his magnum opus , The Theory of Communicative Action .