Evovae is an artificial word made out of the vowels in the words "saeculorum Amen;" which occur at the end of the Gloria Patri. Its object was to serve as a kind of memoria technica to enable singers to render the several Gregorian chants properly; each letter in evovae standing for the syllable from which it is extracted. It must be borne in mind that psalms, etc., were sung under antiphons, and that the music of the antiphon, being constructed in a particular "mode" or "scale," such as Dorian, Phrygian, and the like, the chant or "tone" ("tune") to the psalm, being not intended to represent a fill stop or close, might (and usually did) not end on the final belonging to the mode, leaving that for the concluding antiphon: thus different forms of the same mode or tone would arise, and these were called evovae, and sometimes by other names. This only applies to the latter half (cadence) of the chant, as in the "mediation" (at the middle of the verse of a psalm) scarcely any variety was admitted, except such as arose from local use. Thus, in the various works on the subject, and in service books, varieties of endings are to be found of greater or less antiquity. See Smith, Dict. of Christ. Antiq. s.v.