The Dulcinian sect began in 1300 when Gherardo Segarelli, founder of the Apostolic Brethren, was burned at the stakeinParma during a brutal repression of the Apostolics. His followers went into hiding to save their lives. Fra Dolcino had joined the Apostolics between 1288 and 1292, and became their leader. He published the first of his letters explaining his ideas about the epochs of history based on the theories of Gioacchino da Fiore.
Fra Dolcino, at the beginning of 1303, reunited the Apostolic movement near Lake Garda. He met Margaret of Trent (real name Margherita Boninsegna, his lover or sister in spirit), and wrote the second letter to the Apostolics. At the beginning of 1304, three Dulcinians were burned by the Inquisition, leading Dolcino to evacuate the community to the west side of the Sesia valley, near his native Novara. At the end of 1304, only 1400 survived on the top of Mount Parete Calva, in the fortified Piano dei Gazzari. They descended the mountain to pillage and kill the people in the valley, responsible in their eyes for not defending the group against the episcopal troops. The villagers called them "Gazzari" (Cathars), and joined the soldiers in opposition.
Dolcino justified the acts committed by the Dulcinians by affirming their perfection and holiness based on Saint Paul's Epistle to Titus (1:15):
To the pure all things are pure, but to the corrupt and unbelieving nothing is pure; their very minds and consciences are corrupted.
Boniface's successor: ruin would fall on him and all the cardinals
The new holy pope
Thus, the advent of the "new holy pope" was postponed to the second pope after the death of Boniface VIII. Dolcino never proposed himself as the new Pope in his letters, although this was one of the accusations of the Inquisition.
Bernardo Gui, "De secta illorum qui se dicunt esse de ordine apostolorum"
"Additamentum ad Historiam fratris Dulcini, haeretici" ab auctore coevo scriptum
Muratori L., "Raccolta degli Storici Italiani dal 500 al 1500", collects the previous 3 documents, book IX, part V, Città di Castello, C.E.S. Lapi, 1907.
Johann Lorenz von Mosheim『Geschichte des Apostel-Ordens in dreien Büchern』in "Versuch einer unparteischen und gründlichen Ketzergeschichte", Helmstaedt 1748.
Orioli Raniero, "Venit perfidus heresiarca. Il movimento apostolico-dolciniano dal 1260 al 1307", Roma 1988.
Berkhout, Carl T. and Jeffrey B. Russell. "Medieval heresies: a bibliography, 1960-1979." in Subsidia mediaevalia, 11. Toronto: Pontifical Institute of Mediaeval Studies, 1981 (entries Apostolici, Dolcino, Margaret, Segarelli).