This satirical work is a critique of the practices of the Church and the wider social behavior of the time. Narrated by Folly, the female personification of foolishness, the book humorously criticizes various aspects of society such as superstitious religious practices, scholarly pedantry, and the excesses of the upper classes. The book is a bold critique of its time, using humor and irony to expose the follies of its society.

"The Waning of the Middle Ages" is a historical analysis of the cultural life of the late Middle Ages, particularly in France and the Low Countries, during the 14th and 15th centuries. It delves into the period's modes of thought, forms of expression, religious beliefs, and social norms. The book argues that the era was characterized by a highly stylized and overwrought civilization, marked by an excessive emphasis on chivalry and courtly love, a religious mindset dominated by the fear of death and the afterlife, and a cultural milieu that was both highly imaginative and deeply pessimistic.