Non Clamor Sed Amor

Samuel Longfellow, Life of Henry Wadsworth Longfellow, Vol. 3, Appendix VII, p. 446:

The Motto

Upon one of Mr. Longfellow's book-plates was engraved the motto "Non clamor sed amor." It was taken from the following stanza which he had found, without any author's name, in one of his books: --

"Non vox sed votum,
Non chorda sed cor,
Non clamor sed amor,
Clangit in aure Dei."

Not voice but vow,
Not harp-string but heart-string,
Not loudness but love,
Sounds in the ear of God.

The verse that is Longfellow's motto has been oft-repeated through the ages, and variously attributed to Augustine, the Venerable Bede, Lewis Bayly, Francis Roberts, and others. I have spent some time tracing its origin, and after reviewing the various citations by Bayly, Roberts, and, further back, Jerome Zanchius, and his mentor, Peter Martyr, I think I am able with some confidence to point to the source of this verse as being a medieval gloss on Gratian's Decretum, Distinction 92, Chaps. 1 and 2.

Lewis Bayly, The Practice of Piety (1611), p. 154:

4. As you sing uncover your heads (1 Cor. xi. 4), and behave yourselves in comely reverence as in the sight of God, singing to God in God’s own words; but be sure that the matter make more melody in your hearts (Eph. v. 19; Col. iii. 16) than the music in your ear; for the singing with grace in our hearts is that which the Lord is delighted withal, according to that old verse:

Non vox, sed votum; non miisica chordula, sed cor:

Non clamans, sed amana, psallit in aure Dei.

‘Tis not the voice, but vow;

Sound heart, not sounding string;

True zeal, not outward show,

That in God’s ear doth ring.

Francis Roberts, Clavis Bibliorum: The Key of the Bible (1665), p. 129:

4. Sing with the heart and inward affections, making melody with Grace there to the Lord, as well as with the voice making melody to the outward eare. The Apostle insists in a special manner upon this Direction.
....
d. The Gloss rightly prefers the real heart-melody before the formal Voice-musick: saying;

Non vox, sed votum; non Musica chordula, sed Cor:
Non clamor, sed Amor; Psallit in aure Dei.

Soule's vow, not ayery voice; sound heart, not sounding string:
Pure love, not piercing-noise; in Gods ear sweetly sing.

Jerome Zanchius, Commentarius in Epistolam Sancti Pauli ad Ephesios (1594, 1888 ed.), p. 242:

Multa in hanc sententiam & contra hanc nimis numerosam Musicam scripta legantur in Decret. distinct. 92. Et concluditur ex hoc loco Pauli. corde magis lingua & voce canendum esse Dominio. Et ibidem glossa duos pios versus, quanquam non elegantes.

Non vox sed votum: non chordula Musica sed cor,
Non clamans sed amans cantat in aure Dei.

Peter Martyr, "On Music and Song" ("De Musica et Carminibus") in Commentary on Judges (In Librum Iudicum) (1561), translated by Joseph C. McLelland, in John Patrick Donnelly, S.J., Frank A. James III & Joseph C. McLelland, eds., The Peter Martyr Reader (1999), p. 170:

Augustine adds that those who give greater heed to music than to the words of God sin with penalty, as he puts it. Jerome agrees wholly with this judgment, as he has noted on the letter to the Ephesians.15 Gregory of Rome shared the same opinion, in a synod at Rome. Their words are written in the Decrees, distinction 92, the chapter Cantantes and the chapter In sancta Romana.16 In its gloss we read these two verses, not very eloquent, but devout:

Not the voice, but the desire; not the tune, but the heart;
not being noisy but loving, sounds in God's ear.17

15 Augustine Conf. X.50 (PL 32.800): poenaliter me peccare confiteor; Jerome on Eph. 5.19 has "Let the servant of God sing in such a way that the words of the text rather the voice of the singer cause delight" -- Gratian Dec. I, dist. XCII (PL 187.129ff.).
16 Gratian Dec. I, dist. 92, chaps. 1 and 2 (PL 187.429): corde magis quam voce Deo cantandum meminerint.
17 Non vox, sed votum; non cordula musica, sed cor [vox]; Non clamans, sed amans cantat in aure dei. I follow Anthony Marten's Commonplaces here, substituting cor for vox at the end of the first line, thus offering a better parallel to cordula and contrast to the initial vox.