BNF 1143 is a revision of an earlier version found in Prague, Abbey of Strahov MS D.E.I. 7, and represents the work of Thomas Aquinas following or during his residency at Orvieto from 1259 to 1265. The office can also be found in the 1343 codex Regimen Animarum. This liturgy may be used as a votive Mass of the Blessed Sacrament on weekdays in ordinary time. The hymn Aquinas composed for Vespers of Corpus Christi, Pange Lingua or another eucharistic hymn, is also used on Maundy Thursday during the procession of the Blessed Sacrament to the altar of repose. The last two verses of Pange Lingua are also used as a separate hymn, Tantum Ergo, which is sung at Benediction of the Blessed Sacrament. O Salutaris Hostia, another hymn sung at Benediction of the Blessed Sacrament, comprises the last two verses of Verbum Supernum Prodiens, Aquinas' hymn for Lauds of Corpus Christi. Aquinas also composed the propers for the Mass of Corpus Christi, including the sequence Lauda Sion Salvatorem. The epistle reading for the Mass was taken from Paul's First Epistle to the Corinthians (), and the Gospel reading was taken from the Gospel of John (). When Pope Pius V revised the General Roman Calendar (see Tridentine Calendar), Corpus Christi was one of only two "feasts of devotion" that he kept, the other being Trinity Sunday. In that calendar, Corpus Christi was celebrated on the Thursday after Trinity Sunday. The feast had an octave until 1955, when Pope Pius XII suppressed all octaves, even in local calendars, except those of Christmas, Easter and Pentecost (see General Roman Calendar of Pope Pius XII). From 1849 until 1969, a separate Feast of the Most Precious Blood of Our Lord Jesus Christ was assigned originally to the first Sunday in July, later to the first day of the month. This feast was removed from the General Roman Calendar in 1969, "because the Most Precious Blood of Christ the Redeemer is already venerated in the solemnities of the Passion, of Corpus Christi and of the Sacred Heart of Jesus and in the feast of the Exaltation of the Holy Cross. But the Mass of the Most Precious Blood of Our Lord Jesus Christ is placed among the votive Masses". Celebration Roman Catholic Church The feast of Corpus Christi is one of five occasions in the year on which a diocesan bishop is not