This hymn is exceedingly sublime in its expression of faith in Our Lord in the Blessed Sacrament. The latter part of this hymn is mandated by the Church for use at Benediction of the Blessed Sacrament. The last two stanzas, known as the Tantum Ergo, is usually sung at the beginning of the last part of Benediction; after any period of silence and before the priest blesses the congregation with Our Lord Himself. Even today this hymn is widely known and used frequently. It is one of the most famous chants in existence.
It was written by St. Thomas Aquinas, the Angelic Doctor. He is known as the Common Doctor of the Church. His angelic purity and holiness brought him very close to God. He wrote the hymn Pange Lingua (of which the Tantum Ergo is the last two stanzas) for the feast of Corpus Christi. A fellow priest and close friend attempted this task at the same time. When St. Thomas finished, he shared it with the priest, who was awe-struck at its sublimity and expression. He was so moved by its beauty that he immediately tore up his own work, which he professed was like so much garbage compared to this heavenly-inspired text.
Click here for the Latin lyrics.
English Translation of Pange Lingua:
Sing, my tongue, the Savior's glory,
of His flesh the mystery sing;
of the Blood, all price exceeding,
shed by our immortal King,
destined, for the world's redemption,
from a noble womb to spring.
Of a pure and spotless Virgin
born for us on earth below,
He, as Man, with man conversing,
stayed, the seeds of truth to sow;
then He closed in solemn order
wondrously His life of woe.
On the night of that Last Supper,
seated with His chosen band,
He the Pascal victim eating,
first fulfills the Law's command;
then as Food to His Apostles
gives Himself with His own hand.
Word-made-Flesh, the bread of nature
by His word to Flesh He turns;
wine into His Blood He changes;
what though sense no change discerns?
Only be the heart in earnest,
faith her lesson quickly learns.
Down in adoration falling,
Lo! the sacred Host we hail;
Lo! o'er ancient forms departing,
newer rites of grace prevail;
faith for all defects supplying,
where the feeble senses fail.
To the everlasting Father,
and the Son who reigns on high,
with the Holy Ghost proceeding
forth from Each eternally,
be salvation, honor, blessing,
might and endless majesty.
See more Gregorian chant lyrics and English translations here.