Hauntingly Beautiful Gregorian Chant "Pange Lingua" written by St. Thomas Aquinas for Corpus Christi

"Pange lingua gloriosi corporis mysterium" is a hymn written by Thomas Aquinas (1225–1274) for the Feast of Corpus Christi and it is also sung on Holy Thursday.
The last two verses (are known as the "Tantum ergo") which are sung at Benediction of the Blessed Sacrament.
Latin Lyrics with English translation.
Pange, lingua, gloriósi
Córporis mystérium,
Sanguinísque pretiósi,
Quem in mundi prétium
Fructus ventris generósi
Rex effúdit géntium.

Nobis datus, nobis natus
Ex intácta Vírgine,
Et in mundo conversátus,
Sparso verbi sémine,
Sui moras incolátus
Miro clausit órdine.

In suprémæ nocte coenæ
Recúmbens cum frátribus
Observáta lege plene
Cibis in legálibus,
Cibum turbæ duodénæ
Se dat suis mánibus.

Verbum caro, panem verum
Verbo carnem éfficit:
Fitque sanguis Christi merum,
Et si sensus déficit,
Ad firmándum cor sincérum
Sola fides súfficit.

Tantum ergo sacraméntum
Venerémur cérnui:
Et antíquum documéntum
Novo cedat rítui:
Præstet fides suppleméntum
Sénsuum deféctui.

Genitóri, Genitóque
Laus et jubilátio,
Salus, honor, virtus quoque
Sit et benedíctio:
Procedénti ab utróque
Compar sit laudátio.
Amen. Alleluja.

Sing, my tongue, the Saviour'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 Paschal Victim eating,
First fulfils the Law's command;
Then as Food to all his brethren
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,
When the feeble senses fail.

To the Everlasting Father
And the Son who comes on high
With the Holy Ghost proceeding
Forth from each eternally,
Be salvation, honor, blessing,
Might and endless majesty.
Amen. Alleluia.