The jurisdiction which we have seen the Chancellor wielding in this court had not been always his, and it was acquired not without dust and heat. At the beginning of the thirteenth century he was both in fact and in theory the delegate of the bishop of the diocese; not the presiding head, but an external authority who might be invoked to enforce the decrees of the Masters' Guild. Before that time the organisation of the University extended at least so far as to boast of a "Master of the Schools," who was probably elected by the masters themselves, and whose office was very likely merged into that of the Chancellor. As an ecclesiastical judge, deriving his authority from the Bishop of Lincoln, the Chancellor exercised jurisdiction over students by virtue of their being "clerks," not members of the University. Over laymen he exercised jurisdiction only so far as they were subject to the authority of the ordinary ecclesiastical courts. At Oxford he had no prison or Cathedral dungeon to which he could commit delinquents. He was obliged to send them either to the King's prison in the Castle, or to the town prison over the Bocardo Gate. But from this time forward by a series of steps, prepared as a rule by conflicts between town and gown, the office of Chancellor was gradually raised. First it encroached on the liberties of the town, and then shook itself free of its dependence on the See of Lincoln. The protection of the great, learned and powerful Bishop of Lincoln and the fact that, in the last resort, the masters were always ready to stop lecturing and withdraw with all the students to another town, for the University, as such, had not yet acquired any property to tie them to Oxford, were weapons which proved of overwhelming advantage to the University at this early stage of its existence. Again and again we find that, when a dispute as to police jurisdiction or authority arose between the University and the town, pressure was brought to bear in this way. The masters ceased to lecture; the students threatened to shake the dust of Oxford off their feet; the enthusiastic Grossetete, throwing aside the cares of State, the business of his bishopric, and the task of translating the Ethics of Aristotle, came forward to intervene on behalf of his darling University and to use his influence with the King. The Pope, Innocent IV. (1254), was also induced to take the University under his protection. He confirmed its "immunities and liberties and laudable, ancient and rational customs from whomsoever received," and called upon the Bishops of London and Salisbury to guard it from evil. Against the combined forces of the Church, the Crown, and the evident interests of their own pockets, it was a foregone conclusion that the citizens would not be able to maintain the full exercise of their municipal liberty.