True Devotion to Mary is a 1712 book by Saint Louis de Montfort on the Roman Catholic theme of devotion to the Blessed Virgin Mary.
The book was cited as an influence on the religious beliefs of Pope John Paul II, who borrowed his apostolic motto Totus Tuus from the book.
Written in 1712, the manuscript remained practically unknown for more than a century, when it was discovered by chance in 1842, at the Motherhouse of the Missionaries of the Company of Mary at St. Laurent-sur-Sèvre, France.
True Devotion to Mary attracted attention in the 20th century when in an address to the Montfort Fathers, Pope John Paul II said that reading this book had been a "decisive turning point" in his life.
[4] In his 1987 encyclical, Redemptoris Mater the Pope cited Saint Louis Marie Grignion de Montfort as a teacher of Marian spirituality.