Which 14th-century Italian mystic and Doctor of the Church is known for her letters?

Which 14th-century Italian mystic and Doctor of the Church is known for her letters? Catherine of Siena.

Catherine of Siena was born Caterina di Jacopo di Benincasa in Siena in 1347. A Dominican tertiary rather than a cloistered nun, she became an influential religious writer, mystic, diplomat, and adviser involved in the turbulent politics of the medieval papacy. Her correspondence addressed popes, monarchs, cardinals, civic leaders, and fellow religious figures.

Catherine’s letters were often dictated to secretaries; she learned to write herself only late in life. About 382 letters survive, and they are valued both for their spiritual ideas and as major examples of early Tuscan prose. She urged church reform and pressed Pope Gregory XI to return the papacy from Avignon to Rome in 1376.

Her best-known theological work is The Dialogue of Divine Providence, dictated between 1377 and 1378. Pope Pius II canonized Catherine in 1461, and Pope Paul VI declared her a Doctor of the Church in 1970. She was the second woman to receive that title, only days after Teresa of Ávila.