[4] When Cosimo III de' Medici handed over the monastery del Monte (on San Miniato near Florence, also called Monte alle Croci) to the members of the Riformella, Leonard was sent hither under the auspices and by desire of Cosimo III, and began shortly to hold missions among the people of Tuscany.

Everywhere Leonard made conversions, and was very often obliged both in cities and country districts to preach in the open, as the churches could not contain the thousands who came to listen.

[5] For a time, Leonard was the spiritual director of Maria Clementina Sobieska of Poland, the wife of James Stuart, the Old Pretender.

Leonard founded many pious societies and confraternities, and exerted himself to spread devotion to the Sacred Heart of Jesus, and the perpetual adoration of the Blessed Sacrament.

As a Franciscan priest, he preached the Way of the Cross at missions for forty-three years and reportedly set up stations in over 500 locations throughout Italy, including the Colosseum in Rome.

He arrived on the evening of 26 November 1751, at his beloved monastery of St. Bonaventura on the Palatine, and expired on the same night at eleven o'clock at the age of seventy-four.

[6] The numerous writings of the saint consist of sermons, letters, ascetic treatises, and books of devotion for the use of the faithful and of priests, especially missionaries.

A treasure for asceticism and homiletics, many of his writings have been translated into the most diverse languages and often republished: for example his Via Sacra spianata ed illuminata [7] (the Way of the Cross simplified and explained), Il Tesoro Nascosto (on the Holy Mass); his celebrated Proponimenti, or resolutions for the attainment of higher Christian perfection.

A complete edition of his works appeared first at Rome in thirteen octavo volumes (1853–84), Collezione completa delle opere di B. Leonardo da Porto Maurizio.