Conversation so far:
what was George Steiner's career?
In 1956 George Steiner returned to the United States, where for two years he was a scholar at the Institute for Advanced Study in Princeton, New Jersey.
what did George Steiner do after being a scholar at the Institute for Advanced Study in Princeton, New Jersey?
George Steiner also held a Fulbright professorship in Innsbruck, Austria from 1958 to 1959. In 1959, he was appointed Gauss Lecturer at Princeton, where he lectured for another two years.

Question: what was his greatest accomplishment?
Self-contained rewrite: what was George Steiner's greatest accomplishment?