Praefatio is, in the mass, the prayer which immediately precedes the canon, an exhortation to thankfulness, commencing with the words "Sursum corda." In the Gothic or Mozarabic liturgy the Praefatio is called Illatio; in the Gallican, Immolatio and Contestatio. It is also called Hymnus Angelicus. Originally there was but one praefatio for all days and feasts (Praefatio Communis); since the 12th century a number of prefationes, adapted to the variety of the feasts, the use of which is indicated by the Directory of the Church, have been introduced. Every praefatio ends with the triple "Sanctus," the introduction of which is attributed to Sixtus I. SEE MASS; PREFACES.