As the university developed, it became more institutionalized. First, the professors formed an association, for according to Matthew Paris, John of Celles, twenty-first Abbot of St Albans, England, was admitted as a member of the teaching corps of Paris after he had followed the courses ("Vita Joannis I, XXI, abbat. S. Alban"). The masters, as well as the students, were divided according to national origin. Alban wrote that Henry II, King of England, in his difficulties with St. Thomas of Canterbury, wanted to submit his cause to a tribunal composed of professors of Paris, chosen from various provinces (Hist. major, Henry II, to end of 1169). This was likely the start of the division according to "nations," which was later to play an important part in the university. Celestine III ruled that both professors and students had the privilege of being subject only to the ecclesiastical courts, not to civil courts.