The cover of the book 'The Western Church in the Middle Ages' by John F. A. Mason. The cover features a colorful illustration of a medieval scene with figures in period clothing, including a man in a red robe and a woman in a blue robe, both holding a book. The background shows a richly decorated room with a tapestry and a throne-like chair. The title of the book is prominently displayed in the center at the top, with the author's name at the bottom.