Complex sentence: Goebbels earned a PhD from Heidelberg University in 1921, writing his doctoral thesis on 19th century literature of the Romantic school; he then went on to work as a journalist and later a bank clerk and caller on the stock exchange.
Split into simpler sentences: Goebbels earned a PhD from Heidelberg University in 1921 with a doctoral thesis on 19th-century literature of the Romantic school. He found work as a journalist and later as a bank clerk and caller on the stock exchange.