Pange Lingua Gloriosi Corporis Mysterium is a Latin hymn written by Saint Thomas Aquinas (1225–1274) for the Feast of Corpus Christi. It is also sung on Maundy Thursday during the procession from the church to the place where the Blessed Sacrament is kept until Good Friday. The last two stanzas (called, separately, Tantum Ergo) are sung at Benediction of the Blessed Sacrament. The hymn expresses the doctrine that the bread and wine are changed into the Body and Blood of Christ during the celebration of the Eucharist.