Leaf on vellum from a Dutch manuscript Book of Hours.

A wonderful leaf of a Dutch Book of Hours, written on very fine vellum and decorated with pen work in red, green and purple. The two initials at the top of the recto are in blue paint. The leaf is part of the calendar for the month of April, at the top we read : April heeft xxx daghe, die mane xxix. [ April has 30 days, the moon 29.] Peculiar saints we find on the verso : siderac misa ende abdenago, Sadrach, Mesach and Abednego from the book of Daniel.
A liturgical calendar showing feast days of the church year, both fixed, like Christmas, and ?movable? (depending on cycles of the moon), like Easter. Important feast days were written or printed in red ink, hence the expression, ?red-letter day.?