collegia pietatis, conventicles of Christians meeting to study the Scriptures and devotional literature; the concept was first advanced in the 16th century by the German Protestant Reformer Martin Bucer, an early associate of John Calvin in Strasbourg. Philipp Jakob Spener adopted the idea a century later in an effort to counteract what he perceived as the moral and spiritual indifference of the Protestant churches and to implement a program of reform that revolved around Bible study, devotional exercises, and personal piety. Spener had outlined this reform program in a book entitled Pia Desideria (“Pious Wishes”). This led to a religious revival in many German states and influenced not only the church but also society in general. Because of their emphasis on the practice of a pious life, Spener and his followers were called Pietists.