I. Liturgy

The introit was the first song of the mass, sung during the entrance of the celebrant. It is first attested by the Ordo Romanus Primus and must therefore have been introduced before the end of the 7th century. It comprised an antiphon and a complete psalm when it accompanied a papal procession from the secretarium (sacristy near the entrance). The introit acquired its “Gregorian” form after 750 in France (approx. 150 authentic songs). It still lends its name to Sundays (Laetare, Quasimodo Geniti et al.)…