The Wandering Tone

Most of the psalm tones are homebodies. Each has a single reciting note — a tenor, the pitch on which the bulk of each verse is chanted — and it holds that note faithfully through both halves of the verse, bending only at the mediant and the ending. The tonus peregrinus is the exception. It will not stay put: its second half recites a whole step lower than its first.The tenor drops from la to sol between the two halves of the verse — hence peregrinus, “foreign” or “wandering.” The effect is subtle sung but unmistakable once the ear knows to listen for it.

It is old, and the old theorists already treat it as an oddity — a tone that does not behave, filed among the regular eight with an apology.Already flagged as irregular in the Commemoratio brevis (9th c.); cf. the discussion in Willi Apel, Gregorian Chant (Bloomington, 1958), pp. 208–212, where the tone’s antiquity and its Eastern parallels are laid out at length. By long tradition it is wedded to a single psalm, In exitu Israel — Psalm 113 in the Vulgate numbering — whose opening is itself about going out: Israel leaving Egypt, a people picking up and moving.Vulgate/Septuagint numbering; the Hebrew tradition divides the same material as Pss. 114–115. The association of tone and psalm is ancient and very nearly universal in the Western books. Cf. also the glossary at Beatus vir on the numbering question generally.

I do not think the pairing is an accident, though I cannot prove it was designed. A tone that migrates mid-verse, set to the psalm of a migration; a melody that refuses to settle, carrying the words of a people who could not settle either. Whoever first joined them had an ear not only for pitch but for sense. The wandering is the point.