With a spare elegance, the anonymous illuminator known as the Master of the Brussels Initials decorated the missal's calendar pages, which precede the texts used for the celebration of the Mass throughout the year. The calendar notes the feasts and holidays of the church year. Since the texts of the missal are arranged according to the order in which they were said during the church year, the calendar helped the priest to identify the appropriate prayers for each day. In this missal, the calendar pages are each identified by a zodiacal sign: Aries, indicated by the ram, roughly corresponds to the month of March. The illuminator also included the representation of a Labor of the Month, corresponding to an activity traditionally associated with a particular month. Here a peasant blows two horns, heralding the coming of spring.
The illuminations on this page have a distinctive grace and simplicity. The artist drew from his close observation of nature for the graceful movements of the peasant, his softly falling drapery, and the ram's delicately extended front hoof. The artist also carefully harmonized the colors, using a limited palette of blue, red, brown, and gold to unify the page.