The Black Hours.

This is something I only became aware of a few years ago. During the 15th century in in Burgundy, especially during the time of Philip the Good, there was a trend of making luxury manuscripts on vellum that had been dyed black. Unfortunately, the process of dying the vellum made it brittle and fragile, so these manuscript did not survive in great numbers. There are fewer than twenty surviving manuscripts and only three of them are still bound as codices. The remainder are preserved as single leaves, often pressed in acrylic to protect them. So far as I know, all of the surviving examples are Books of Hours. The Pierpont Morgan Library has one, and this is a two page spread from it. The illumination on the left is of the Descent of the Holy Spirit.

While I'm not a huge fan of Books of Hours, this is certainly striking.