Illuminated Manuscript Mystery

What does this image portray?  What is the book?  In what language is it written?  This is an extremely tough one.  Hint: I took this grainy picture, under the grumpy but indulgent supervision of some surly guards, at The Cloisters today.  The winner receives the MOJ honorary crown of holy laurels and will hereafter be designated "Magnus Illuminatus" (or, as circumstance demands, "Magna Iluminata") by the extended MOJ community.  Buena Suerte!  [UPDATE: For some reason, I have been having trouble opening comments to my posts.  Just shoot me an email if you want to make a guess, even a bad one.]

ANSWER: The image is of a page of a late 15th century translation into Spanish of St. Augustine's De Civitate Dei.  The translation is by "Cano de Aranda and workshop" for Alfonso Carillo de Acuña, archbishop of Toledo.  Congratulations to the trio of maximi illuminati: Ben Brady, Not the other Joe, and our own Father Araujo.  Crowns of laurels in the mail.