On April 28, the universal Church celebrates the feast day of Louis-Marie de Monfort, a 17th century saint who is revered for his intense devotion to the Blessed Virgin Mary.

St. Louis-Marie is perhaps most famously known for his prayer of entrustment to Our Lady, “Totus Tuus ego sum,” which means, “I am all yours.” The late-Pope John Paul II took the phrase “Totus Tuus” as his episcopal motto.

Born in Montfort, Brittany, on January 31, 1673, St. Louis-Marie possessed a strong devotion to the Blessed Sacrament as a child, and was also intimately devoted to the Blessed Virgin, especially through the Rosary. He took the name Marie at his confirmation.

The saint manifested a love for the poor while he was at school and joined a society of young men who ministered to the poor and the sick on school holidays. When he was 19, he walked 130 miles to Paris to study theology, gave all he had to the poor that he met along the way and made a vow to live only on alms. After his ordination at 27, he served as a hospital chaplain until the management of the hospital resented his reorganization of the staff and sent him away.

St. Louis-Marie discovered his great gift for preaching at the age of 32, and committed himself to it for the rest of his life. He met with such great success that he often drew crowds of thousands to hear his sermons in which he encouraged frequent communion and devotion to Mary.

But he also met with opposition, especially from the Jansenists, a heretical movement within the Church that believed in absolute Predestination, in which only a chosen few are saved, and the rest damned. Much of France was influenced by Jansenism, including many bishops, who banished St. Loius-Marie from preaching in their dioceses. He was even poisoned by Jansenists in La Rochelle, but survived, though he suffered ill health after.

While recuperating from the effects of the poisoning, he wrote the masterpiece of Marian piety, "True Devotion to the Blessed Virgin," which he correctly prophesied would be hidden by the devil for a time. His seminal work was discovered 200 years after his death.

One year before he died, St. Louis-Marie founded two congregations: the Daughters of Divine Wisdom – which tended to the sick in hospitals and the education of poor girls, and the Company of Mary, missionaries devoted to preaching and to spreading devotion to Mary.