Before tracking it to its source I guessed that it dated to the sixteenth century. I showed it to my elder daughter, fresh out of college with a shiny new degree, and she said, "late fifteenth, maybe early sixteenth." You let these kids out of your sight and soon they come back knowing more than you do.
Even the ordinary pages in this book of hours are decorated with these marvelous doodles; a doodler myself, I am awed by the virtuosity displayed here.
I found lots of other manuscripts in the course of this exercise, so there will be more in days to come.