Members of King's were to be recruited entirely from Eton. Each year, the provost and two fellows travelled to Eton to impartially select the worthiest boys to fill any vacancies at the college, always maintaining the total number of scholars and fellows at exactly seventy. Membership of King's was a vocation for life. Scholars were eligible for election to the fellowship after three years of probation, irrespective of whether they had achieved a degree or not. In fact, undergraduates at King's – unlike those from other colleges – did not even have to pass university examinations to achieve their BA degree and instead had only to satisfy the college. Every fellow was to study theology, save for two who were to study astronomy, two civil law, four canon law, and two medicine; all fellows save those studying secular subjects were obliged to take Holy Orders and become priests, on pain of expulsion. In 1445, a Papal Bull from Eugenius IV exempted college members from parish duties, and in 1457, an agreement between the provost and chancellor of the university limited the chancellor's authority and gave the college full jurisdiction over internal matters.