Preacher and ascetic writer, born 20 December 1676, at Porto Maurizio on the Riviera di Ponente; died at the monastery of San Bonaventura, Rome, 26 November 1751. The son of Domenico Casanova and Anna Maria Benza, he joined after a brilliant course of study with the Jesuits in Rome (Collegio Romano), the so-called Riformella, an offshoot of the Reformati branch of the Franciscan Order. On 2 October 1697, he received the habit, and after making his novitiate at Ponticelli in the Sabine mountains, he completed his studies at the principal house of the Riformella, S. Bonaventura on the Palatine at Rome. After his ordination he remained there as lector (professor), and expected to be sent on the Chinese missions. But he was soon afterwards seized with severe gastric haemorrhage, and became so ill that he was sent to his native climate of Porto Maurizio, where there was a monastery of the Franciscan Observants (1704). After four years he was restored to health, and began to preach in Porto Maurizio and the vicinity. When Cosimo III de’ Medici handed over the monastery del Monte (that on San Miniato near Florence, also called Monte alle Croci) to the members of the Riformella, Saint Leonard was sent hither under the auspices and by desire of Cosimo III, and began shortly to give missions to the people in Tuscany, which were marked by many extraordinary conversions and great results. His colleagues and he always practised the greatest austerities and most severe penances during these missions. In 1710 he founded the monastery of Icontro, on a peak in the mountains about four and a quarter miles from Florence, whither he and his assistants could retire from time to time after missions, and devote themselves to spiritual renewal and fresh austerities.
In 1720 he crossed the borders of Tuscany and held his celebrated missions in Central and Southern Italy, enkindling with zeal the entire population. Clement XII and Benedict XIV called him to Rome; the latter especially held him in high esteem both as a preacher and as a propagandist, and exacted a promise that he would come to Rome to die. Everywhere the saint made abundant 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. He founded many pious societies and confraternities, and exerted himself especially to spread the devotion of the Stations of the Cross – the propagation of which he greatly furthered with the assistance of his brethren – the devotion to the Sacred Heart of Jesus, the perpetual adoration of the Most Blessed Sacrament, and devotion to the Immaculate Conception. One of his most ardent desires was to see the last-named defined as a dogma of faith by the Holy See. Besides the celebrated stations in the Colosseum at Rome, Saint Leonard erected 571 others in all parts of Italy, while on his different missions. From May to November, 1744, he preached in the Island of Corsica, which at that time belonged to the Republic of Genoa and which was frightfully torn by party strife. In November 1751, when he was preaching to the Bolognese, Benedict XIV called him to Rome, as already there were indications of his rapidly approaching end. The strain of his missionary labours and his mortifications had completely exhausted his body. He arrived on the evening of 26 November, 1751, at his beloved monastery of S. Bonaventura on the Palatine, and expired on the same night at eleven o’clock at the age of seventy-five. In the church of this monastery (which must soon make way for the excavations of the ground occupied by the palace of the Caesars) the partly incorrupt body of the saint is kept in the high altar. Pius VI pronounced his beatification on 19 June, 1796, and Pius IX his canonization on 29 June, 1867. The Franciscan Order celebrates his feast on 26 November, but outside this order it is often celebrated on 27 November.
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. The “Diary” (Diario) of his missions is written by Fra Diego da Firenze. 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 Sacrea spianata ed illuminata” (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”. Then another in five octavo volumes, “Opere complete di S. Leonardo di Porto Maurizio” (Venice, 1868-9). In English, German, etc., only single works have been issued, but a French translation of the entire set has appeared: “OEuvres completes de S. Leonard de Port-Maurice”, and “Sermons de S. Leonard de Port Maurice”.