The leaf, from a splendid illuminated choirbook linked to Perugia, was purchased at Sotheby’s, Western & Oriental Manuscripts auction, 8 July 2008 (lot 7).

Contents: The music and words of the introit sung at the Vigil Mass on the eve of the Feast: antiphon Dicit Dominus Petro (incomplete), psalm verse Celi enarrant gloriam and Gloria Patri, following to the gradual In omnem terram, offertory Michi autem and communion antiphon Simon Iohannis diligis me. A large historiated initial `N' introduces verse 11 from the Acts of Apostles 12 set to form the entrance antiphon for Mass on the Feast day. 

Decoration: Historiated initial 'N' frames Saint Peter holding his keys, St Paul with his sword, and God above bearing witness. Ants carrying seeds are pictured in the bas-de-page. Two large initials, alternately red and blue and flourished in the reverse colour, introduce the psalm verse and communion antiphon.

The illustration is attributed to a follower of Matteo Ser Cambio, a panel painter and illuminator active in Perugia between 1356-1424.