The first Sunday after Pentecost. Its origins go back to the Arian heresy, when an office with canticle, responses, preface, and hymns was composed by the Fathers and recited on Sundays. Bishop Stephen of Liège (903-20) wrote an office of the Holy Trinity that in some places was recited on the sunday after Pentecost, and elsewhere on the last sunday before Adven. St. Thomas à Becket (1118-70), consecrated Archbishop of Canterbury on the Sunday following Pentecost, obtained for England the privilege of a special feast to honor the Trinity on that day. Pope John XXII (reigned 1316-34) extended the feast to the universal Church.