Complex sentence: In 1952 Mr. Seaver wrote an essay lauding the work of a young, then-unknown novelist Samuel Beckett, that became instrumental in Beckett's finding an American publisher and champion.
Split into simpler sentences: In 1952 Mr. Seaver wrote an essay lauding the work of a young, then-unknown novelist Samuel Beckett. This essay became instrumental in Beckett's finding an American publisher and champion.