Unusually, he spent his entire academic life in the faculty of arts, rather than obtaining the doctorate in law, medicine or theology that typically prepared the way for a career in philosophy. Also unusual for a philosopher of his time, Buridan further maintained his intellectual independence by remaining a secular cleric, rather than joining a religious order. A papal letter of 1330 refers to him as simply, " clericus Atrebatensis diocoesis, magister in artibus [a cleric from the Diocese of Arras and Master of Arts]." As university statutes permitted only those educated in theology to teach or write on the subject, there are no writings from Buridan on either theological matters or commentary of Peter Lombard 's Sentences.