Complex sentence: In 1947 he returned to Cornell for a semester to obtain his B. A. degree, then began studies at Columbia University for his M. A. and PhD in English Literature, where he was influenced by Lionel Trilling and Jacques Barzun.
Split into simpler sentences: In 1947 he returned to Cornell for a semester to obtain his B. A. degree. He then began studies at Columbia University for his M. A. and PhD in English Literature, where he was influenced by Lionel Trilling and Jacques Barzun.