What a striking contrast between cultures: a rich man hires artists to painstakingly craft a sacred book that only few eyes could view, versus today's universal access to the world's splendors. It is yet another fulfillment of Daniel's prophecy of exponentially-increasing knowledge.
These devotional Books of Hours were for private use. There are beautiful other examples, all done for the aristocracy. Without their commission, we would not have such treasures around. Today they can be admired in Museums all over the world.