Why did Goodman leave Penn?

Jonathan Strassfeld is working on a doctoral dissertation in the History Department at Rochester on the history of philosophy in mid-20th-century America, especially an institutional history about the leading departments and their areas of focus.  I've been helping him at various intervals with questions about faculty rosters, tenure status, and the like.  He recently wrote with a question to which I don't know the answer, but perhaps some readers can help:   "What were the circumstances leading to Nelson Goodman's exit from Pennsylvania's philosophy department?"   I believe he initially went to Brandeis, then to Harvard.  I have a dim recollection that Penn in the 1950s and 1960s was, like Yale, resisting the turn to "analytic" philosophy, with a large coteria of folks working in "classical" American philosophy.  But I am not at all confident about any of this.  Anyone know?  Signed comments very strongly preferred, since Mr. Strassfeld would like to be able to follow up with knowledgealbe individuals.