Plenarium, a book of formulae and texts. Plenarium or Plenarius (Liber) is any book that contains completely all matters pertaining to one subject otherwise found scattered in several books. Thus, in the life of Bishop Aldrich (Baluze, “Miscell.”, I, iii, 29) we read of a Plenarium, or Breviarium, which seems to be a book of church rents (Binterim, “Denkwurdigkeiten”, IV, i, 239). The entire mortuary office, Vespers, Matins, Lauds, and Mass, is called Plenarium. A complete copy of the four Gospels was called an “Evangeliarium plenarium”. Under this heading we might class the “Book of Gospels” at Lichfield Cathedral, and the “Book of Gospels” given by Athelstan to Christ church in Canterbury, now in the library of Lambeth Palace (Rock, “Church of our Fathers”, I, 122). Some Plenaria gave all the writings of the New Testament, others those parts of the Sacred Scriptures that were commonly read in the Divine service and bore the name “Lectionarium plenarium” (Becker, “Catal. bibl. ant.”, 1885, 28, no. 237; 68, no. 650, 659). When priests in their missionary labors began to be scattered singly in different places, and when, in consequence, co-celebration of the Sacred Mysteries was rendered impossible, and private Masses became more frequent, the complete Missal or “Missale pienarium” came into use. Early vestiges of it may be found in the ninth century, and in the eleventh or twelfth century the “Missale plenarium” was found everywhere and contained all necessary prayers for the celebration of the Holy Sacrifice, which until then had to be taken from different books, the “Sacramentary”, “Lectionary“, “Evangelistary”, “Antiphonary“, and “Gradual” (Zaccaria, “Bibl. fit.”, I [Rome, 1876], 50). In Germany the name Plenarium denoted a popular book, giving the German translation of the Epistles and Gospels for the Sundays and festivals of the entire year together with a short exposition and instruction. Later editions add also the Introit, Gradual etc., of the Masses. The last book of the kind bearing the title Plenarium was printed in 1522 at Basle.