Mercury (?); Zodiacal Sign of Taurus

The bust-length figure carrying a caduceus on this calendar page may be Mercury, the Roman god of war associated with the month of May. As was traditional with calendars in religious service books, some feasts are highlighted, here with red or blue ink, and the most important are in capital letters. The feast of the Ascension, for example, is written in capitals with alternating colors.

A bull in a medallion represents the month's zodiacal sign of Taurus.