Notker of St Gall's Letter Describing the Significative Letters
“Notker sends greeting to brother Lantbert.
At your request, I have taken pains to explain as well as I could what is signified by the single letters place above the neumes (cantilenae.)
‘A’ admonishes the singer that the note must be raised higher/louder (altius.) ‘B,’ according to the letters to which it is attached, signifies that the note rises or falls much further, or is held longer in a strident voice (belgicat.) ‘C’ certifies that a note is performed quickly or rapidly. ‘D’ demonstrates that a note goes lower. ‘E’ elegantly explains that a note is sounded evenly/equally/at the same pitch. ‘F’ furiously demands that the note shall be begun with a harsh sound or the sound of gnashing teeth. ‘G’ genuinely grants that a note is to gargled gradually in the throat. ‘H’ heralds that one aspirates on the note itself in the manner that one does when pronouncing this letter. ‘I’ indicates a lowering of the sound with the heaviness of the letter ‘g.’ ‘K’ for the Latins has no value, but among us Alemanni it replaces the greek χ, signifying ‘klenche’, that is, a ringing sound. ‘L’ delights to lighten/raise the sound. ‘M’ mentions that the melody is moderated with supplication. ‘N’ signifies to take note of this. ‘O’ ordains that the mouth of the singer should resemble the letter itself. ‘P’ proclaims seizing or grasping the note. ‘Q’ Query: what is the signification of this letter for notes, when even in words it is written only in order that the following ‘u’ may lose strength? ‘R’ requires rectitude: the note must be shaven not to abolition but to a neat curl. ‘S’ shows that the note climbs upwards with a sibilant sound. ‘T’ testifies that the note must be lengthened or held. ‘V’ the value of this letter is that the force of the ‘v’ sound is diminished and is pronounced just as ‘vau’ in Greek or Hebrew. ‘X’ Although Latin words do not being by X itself, nevertheless it expects that one should wait. ‘Y’ Among Latin speakers ‘y’ sings no hymn. ‘Z’ is purely Greek and by reason of this it is not at all necessary for the Romans. Nevertheless, it was taken over as aforesaid by the letter ‘R’, to inquire after other things, which is ‘zitise’ in one’s own language. (Timothy McGee here adds a footnote - ‘This alludes to the fact, known to the Romans, that intervocalic R in Latin had replaced an earlier Z sound.)”
“Notker Lantberto fratri salutem.
Quid singulae litterae in superscriptione significent cantilenae, prout potui iuxta tuam petitionem explanare curaui.
‘A’ ut altius eleuetur admonet. ‘B’ secundum litteras quibus adiungitur, ut bene id est multum extollatur uel grauetur siue teneatur belgicat. ‘C’ ut cito uel celeriter dicatur certificat. ‘D’ ut deprimatur demonstrat. ‘E’ ut equaliter sonetur eloquitur. ‘F’ ut cum fragore seu frendore feriatur efflagitat. ‘G’ ut in gutture gradatim garruletur genuine gratulatur. ‘H’ ut tantum in scriptura aspirat, ita et in nota idipsum habitat ‘I’ iusum uel inferius insinuat, grauitudinemque pro g interdum indicat. ‘K’ licet apud latinos nihil ualeat, apud nos tamen alemannos pro x greca positum, klenche id est clange clamitat. ‘L’ leuare laetatur. ‘M’ mediocriter melodiam moderari mendicando memorat. ‘N’ notare hoc est noscitare notificat. ‘O’ figuram sui in ore cantantis ordinat. ‘P’ pressionem uel prensionem predicat. ‘Q’ in significationibus notarum cur quaeratur ? cum etiam in uerbis ad nihil aliud scribatur nisi ut sequens u uim suam amittere queratur. ‘R’ rectitudinem uel rasuram non abolitionis sed crispationis rogitat. ‘S’ susum uel sursum scandere sibilat. ‘T’ trahere uel tenere debere testatur. ‘U’ licet amissa ui sua, ualde ueluti uau greca uel hebrea uelificat. ‘X’ quamuis latina per se uerba non inchoet, tamen expectare expetit. ‘Y’ apud latinos nihil ymnizat. ‘Z’ uero licet et ipsa mere greca, et ob id haut necessaria romanis, propter praedictam tamen r litterae occupationem, ad alia requirere, in sua lingua zitîse.”
Latin from Jacques Froger, "L'Épitre de Notker sur les 'Lettres significatives': Édition critique," Études grégoriennes 5 (1962). Translation from Timothy Mcgee, The Sound of Medieval Song: Ornamentation and Vocal Style According to the Treatises (Oxford: Clarendon Press, 1998).
The extract below is the beginning of the Gradual ‘Tu Es Deus’ from the ‘Cantatorium of St. Gall,’ Codex Sangallensis 359. The significative letters described in the passage above can be seem written just above the neumes themselves.