The Mantellate of Siena, laywomen who wore the Dominican habit but lived in their own homes, were mostly widows. Catherine Benincasa, a dyer's daughter, joined them in her teens, around 1364 or 1365, after her family had spent years pressing her to marry. For about three years she lived as a recluse in a single room of a crowded house near the Fontebranda fountain, speaking to almost no one but her confessor. In the summer of 1370 she reported a command to leave that room for public life, and she spent the ten years left to her in prisons, in plague wards and at the papal court.
What she carried out of the room became the core of her teaching. She called it the cell of self-knowledge: an inner room a person keeps wherever they go. Anyone who looks honestly at themselves, she argued, finds two things at once: that they did not make themselves, and that they have been given everything. The first, seen alone, leads to despair; the second, to presumption; held together, they produce humility. From humility comes discretion, the practical judgement that gives God, oneself and other people each their due. Penances and fasts count only as tools, because what God asks for is not a finite effort but a desire that has no ceiling. And since no one can repay God directly, the Dialogue, her one book, has God say that he has set people among their neighbours to do for them what they cannot do for him. The same book pictures Christ as a bridge between heaven and earth, crossed in stages, and her letters open by announcing that she writes in his blood.
The world she walked into made that teaching political. The popes had lived at Avignon for some seventy years, and in 1375 Florence formed a league of Italian cities against the papacy; the war that followed became known as the War of the Eight Saints. Catherine told Gregory XI that his own legates had provoked the revolt, and urged him to return to Rome and reform a clergy she accused of buying its offices. In June 1376 she went to Avignon as Florence's envoy. The mediation failed completely, but Gregory left for Italy that September and entered Rome in January 1377.
The pope's return did not bring peace. Gregory died in March 1378 and Urban VI succeeded him. In June, during a popular rising in Florence, an attempt was made on her life, and that year she finished dictating the Dialogue to her secretaries. In August the cardinals declared Urban's election void, and in September they chose Robert of Geneva, the cardinal whose troops had massacred the town of Cesena the year before, as Clement VII. The Great Schism had begun. Urban summoned Catherine to Rome in November, and she spent her last eighteen months writing to kings, cities and cardinals to hold them to Urban, and writing to Urban to moderate his harshness. She died in Rome on 29 April 1380, aged thirty-three.
Much of her record is still argued over. Raymond of Capua, her confessor and later her biographer, recorded that at Pisa in 1375 she received the wounds of Christ, invisible at her own request; she never mentions them herself, and the Franciscans, who held the stigmata to be their founder's privilege, contested the claim, backed later in the fifteenth century by a Franciscan pope, Sixtus IV. Scholars also disagree about how far she could write and how far her secretaries shaped her words, and in 1985 the historian Rudolph Bell read her fasting beside modern anorexia, a reading others have rejected. The Sienese pope Pius II canonised her in 1461, Pius XII made her patron of Italy with Francis of Assisi in 1939, and in 1970 Paul VI named her a Doctor of the Church, a week after Teresa of Ávila, the first two women to hold the title. In 1999 John Paul II made her one of the patron saints of Europe.