The medieval era was the heyday of illuminated manuscripts. In the 14th and 15th centuries, there was a flowering of religious texts set into beautifully-decorated pages. Among these devotional books were psalters, or books of psalms. Hundreds of these were produced, but the Luttrell Psalter is remarkable for its whimsical, humorous and vivid pictures of rural life and a demonic world that is terrifying and grotesque.