Popes, Decretals and Church Agreements: Ten Church Documents from the Liber Pontificalis to Pope Francis

The Liber Pontificalis, Latin for Book of the Popes, collects biographies of the popes from Saint Peter through the fifteenth century. It began as a list of bishops in the third century and was later extended between roughly 1100 and the fifteenth century. Each entry typically records details such as the pope's birthplace, the length of his pontificate and his burial, which makes it the long running record this path begins with.

The Summa Parisiensis is an anonymous commentary on the Decretum Gratiani written around 1170. The Decretum was the twelfth century compilation of canon law that became the standard textbook of medieval church law, and this gloss explains it passage by passage. It shows how Gratian's text was read and taught in the decades just after it was compiled.

Spondent quas non exhibent is a papal decretal issued by Pope John XXII in 1317 that forbade the practice of alchemy. Its target was fraud, the sale of false gold or silver, and it set penalties by the value of the counterfeit metal. It is often cited as church hostility to early chemistry, though the entry notes that it aimed at deception and that John XXII himself had studied chemistry.

Sponsa Christi, meaning Spouse of Christ, is an Apostolic Constitution issued by Pope Pius XII on 21 November 1950. It addresses the vocation of nuns to a life of virginity. It is the stop where the path moves from medieval law to the legislation of the modern papacy.

Communio et Progressio is a pastoral instruction issued by the Pontifical Council for Social Communications on 23 May 1971, prepared in line with the Second Vatican Council's 1963 decree Inter Mirifica. It recognizes freedom of information and the legitimate independence of journalists and media institutions, and it came after the church had given up the general use of the nihil obstat, the imprimatur and the Index to control publications.

The Charter of the Rights of the Family was presented by the Holy See on 22 October 1983 to all persons, institutions and authorities concerned with the family. Its preamble describes the family as founded on marriage and as a natural society that exists prior to the state, with its own inalienable rights. The Holy See addressed it to the wider world rather than to the church alone.

A Formula of Agreement is an ecclesiastical agreement that establishes full communion between three Reformed church bodies in the United States, the Presbyterian Church (U.S.A.), the Reformed Church in America and the United Church of Christ, and the Evangelical Lutheran Church in America. It is the one stop on the path that is not papal, and it shows church documents of the same kind being made between Protestant churches.

Orientations for the Chinese Clergy is a document of the Holy See dated 28 June 2019 and published in full on the Vatican's official news site on the Feast of the Sacred Heart. It answers questions from Chinese bishops about conscience and conscientious objection, and it gives guidance on the civil registration that Chinese law requires of religious leaders.

Aperuit illis is an apostolic letter issued motu proprio by Pope Francis on 30 September 2019, the feast of Saint Jerome. It set up the Sunday of the Word of God on the Third Sunday of Ordinary Time, devoted to celebrating, studying and spreading the Bible. The first such Sunday was observed on 26 January 2020, and the pope said he acted after requests from around the world.

Totum Amoris Est, meaning Everything Pertains to Love, is an Apostolic Letter of Pope Francis marking the fourth centenary of the death of Saint Francis de Sales, a Doctor of the Church. It closes the path with a letter that looks back four hundred years to a single teacher, much as the Liber Pontificalis at the start looked back over the popes.