The Apostolic Constitutions and Exhortations of John Paul II and Benedict XVI (51 vols.) contains the most important writings of the two pontiffs, next to their encyclical letters. The papal office holds the highest teaching authority in the Catholic Church, and the popes realize this office through a number of channels and through the promulgation of a variety of documents. The most famous of these are the papal encyclical letters, which express the pope’s mind normally on matters of faith and morals. Apostolic exhortations often concern similar topics but do not define doctrine and are normally directed at encouraging certain groups within the Church to certain activities. In recent decades apostolic exhortations have most often been issued at the conclusion of synods of bishops and have served as the popes’ summations and interpretations of those synods’ conclusions. Apostolic constitutions, however, are more juridical in nature. They are formal papal decrees and carry the highest authority. Apostolic constitutions can deal with the structure of the Church, but also the liturgy, pastoral, or dogmatic concerns. Together with encyclicals, apostolic exhortations and constitutions are the most important documents produced by the Holy See, touching all matters of ecclesiastical government and doctrine.