Hymn of St. John the Baptist
As you already know, the syllables used to
denote the tones are: Ut, Re, Mi Fa, Sol, La.
They were taken from the first stanza of
the hymn to St. John the Baptist:
Ut queant laxis Resonare fibris
Mira gestorum Famuli tuorum
Solve polluti Labii reatum
Sancte Iohannes
Literal translation from Latin: “So that we, the
servants of the divine, may sing with tuned
voices, and bring ourselves in resonance with
the wonders of your vibrational universe.”