Religious institutes whose members are bound by vows, live in community, and engage in a variety of pastoral work. The term implies that the majority of members are priests or those studying for the priesthood, and that they follow a regulated form of life embodied in detailed constitutions. Originating in the sixteenth century, Clerks Regular became the spearhead of the Counter-Reformation in the Catholic Church's conflict with Protestantism. They included the Theatines, the Clerks Regular of the Good Jesus and the Barnabites. The best known are the Jesuits. Since the close of the sixteenth century, there have been no official additions of Clerks Regular in the Catholic Church, but their rule and way of life have been adopted by many modern congregations of men and modified for adaptation by religious communities of women. They may be regarded as the modern equivalent of the regular canons, whose origin goes back to St. Augustine.