The text is of course that of St. Jerome, the Latin Vulgate, standard in Europe for a thousand years before the Reformation. Note the way the text is surrounded and interlineated with glosses and commentaries from Bede, Jerome, Gregory and other Church Fathers.
Matthew writing his gospel at the dictation of an angel. The text is written in the italic style. Note the Celtic strapwork decoration on the illuminated letter "I".
This is a manuscript in the "rotunda" hand, written on vellum by Carthusian monks; note the simple music line of plainchant at the foot of the page, and the red ("rubricated") initial letters.