Academic freedom arose as a prominent ideal at major American schools in the early twentieth century and with the founding of the American Association of University Professors (AAUP) in 1915. The concern was to exclude outside interests of business or religion from limiting academic freedom, as had sometimes happened. As John Dewey advocated, scientifically trained experts should be free to rule. Schools with religious heritage often had both proclaimed the freedom of professors and expected some religiously defined limits on their teaching. That was well illustrated in the controversy at Lafayette College when a conservative Presbyterian president fired a controversial professor. The ideal of academic freedom was elusive, however, because freedom always had limits as was illustrated by the controversies over national loyalty of professors during World War I. The AAUP eventually allowed religious limits on freedom if they were clearly stated in advance.