Recently, the interest in the 18 months of the annual Aztec calendar, also called xihuitl (365-day year) in Nahuatl, has grown significantly. John Schwaller's book The Fifteenth Month offers an example of this increasing interest and proposes an overview of Panquetzaliztli, a festival celebrated over the 20 days of the 15th month of the Aztec calendar. This study covers all available sources and analyses, as well as all social, economic, and religious aspects of Panquetzaliztli. Furthermore, Schwaller deals with certain issues that have not received much attention from scholars, such as the variety of rituals among the Nahuas of central Mexico and their transformations over time.
The book is organized into an introduction and six chapters. Chapter 1 discusses several sources that describe aspects of the festival that were carried out outside Tenochtitlan, principally the Memoriales of Fray Toribio de Benavente (known as Motolinía), one of the first Franciscan missionaries...