We have previously shown that the bishop of a diocese was originally personally responsible for the preparation of those candidates whom he subsequently ordained. With the progress of time and the increase in the duties of the episcopate, it was impossible for the bishop to undertake the personal responsibility for this work, and consequently a tendency arose for it to be entrusted to a member of the collegiate body associated with him. In the case of a secular bishop, a member of the Cathedral body was appointed. This officer was definitely known as the "Scholasticus," and it was his recognised duty to read theology with approved students. We are able to trace the existence of a "scholasticus" in connection with the English cathedrals from an early date. Thus we learn that when Thurstan, Archbishop of York, visited the Pope at Blois in 1120, he was accompanied by "duo archidiaconi ecclesiae nostrae et scholasticus."[206] We also know that a "scholasticus" existed in connection with St. Paul's, London, because the expression "magister scolarum" occurs in a deed whose date is assigned to c. 1110.[207] In course of time the term "chancellor" was substituted for that of "scholasticus," probably because the schoolmaster was the most highly educated member of the cathedral staff and was therefore the most suitable person to entrust with the care of the cathedral seal and with the dispatch of the official letters of the cathedral body. This statement is definitely established by the statutes of the Church of York, which date from 1307 but which are regarded by their editor as existing from 1090 at least. On page 6 of these statutes it is stated that "Cancellarius, qui antiquitus magister scolarum dicebatur, magister in theologia esse debet, et juxta ecclesiam actualiter legere." The same change of term can be traced at St. Paul's, London. One of the witnesses to a deed dated about 1205 who describes himself as Chancellor is the same person who, when acting in a similar capacity at an earlier date, described himself as "magister scolarum."[208]