Tantum Ergo

I woke around 3:30 last night with the opening words of a famous verse composed by Thomas Aquinas and sung at mass at the benediction of the Blessed Sacrament: Tantum ergo Sacraméntum. The meter, four-beats and then three-and-a-half, alternating, was also in my memory together with a vague sense of the music as well. That whole experience goes back roughly to my twelfth or thirteenth year of life.
So where did this come from suddenly? Questions of this kind can’t be precisely answered, but it occurred to me this morning that struggling with translating Latin into English four days ago may have set tendril of memory vibrating at an unaccustomed wavelength—right back to the time when I was studying Latin and, incidentally, singing hymns in Latin as well. It took a while, and I had to be asleep, before the answer echoed back—to a question I cannot formulate.
Herewith the two stanzas of Tantum Ergo—which conclude a much longer hymn called Pange Lingua Gloriosi Corporis Mysterium. The translation is by Fr. Edward Caswall.
Tantum ergo Sacraméntum Down in adoration falling, Venerémur cérnui: This great Sacrament we hail, Et antíquum documéntum O'er ancient forms of worship Novo cedat rítui: Newer rites of grace prevail; Præstet fides suppleméntum Faith will tell us Christ is present, Sénsuum deféctui. When our human senses fail.

Genitóri, Genitóque To the Everlasting Father, Laus et jubilátio, And the Son who made us free Salus, honor, virtus quoque And the Spirit, God proceeding Sit et benedíctio: From them Each eternally, Procedénti ab utróque Be salvation, honour, blessing, Compar sit laudátio. Might and endless majesty. Amen. Alleluja. Amen. Alleluia.
What a glorious—and compressed sort—of language Latin is!