The hymn Tantum Ergo pays homage to our Lord both in the Eucharist and in His glory in the Trinity. It comprises the last two stanzas of Pange Lingua, a hymn written by Saint Thomas Aquinas for the Feast of Corpus Christi (which honours our Lord in His body and blood in the Eucharist) when it was first instituted by the Church in 1264. This text has been set to music by composers as diverse as Palestrina, Mozart, Bruckner and Fauré.
This hymn plays an important part in the Rite of Eucharistic Exposition and Benediction of the Blessed Sacrament. In this rite, people worship our Lord in the monstrance, a vessel placed on the Altar in church, with prayers, hymns and time for silent meditation before Him. Tantum Ergo is usually sung before the Benediction when the priest blesses the congregation with the monstrance.
It is also sung as part of Pange Lingua, during processions of the Blessed Sacrament.
Therefore we, before Him bending,
This great Sacrament revere;
Types and shadows have their ending,
For the newer rite is here;
Faith, our outward sense befriending,
Makes our inward vision clear.
Glory let us give and blessing
To the Father and the Son,
Honour, thanks, and praise addressing,
While eternal ages run;
Ever too His love confessing
Who from Both with Both is One.