European universities had great intellectual and religious influence in the Renaissance and Reformation and exhibited considerable variety. Italian universities taught law and medicine to doctoral students. Their loose organization made t possible for professors to produce original research in law, medicine, philosophy, and the humanities. Northern European universities concentrated on teaching arts to undergraduates, while theology was the most important graduate faculty. Their stronger structure enabled Martin Luther and other professors of theology in German, Dutch, Swiss, and English universities to create and lead the Protestant Reformation. By the early seventeenth century universities everywhere were in decline.