Leonia Nastał (born Maria Nastał; 8 November 1903 – 10 January 1940) was a Polish religious sister from the Congregation of the Sisters Handmaids of the Blessed Virgin Mary Immaculate, a mystic, religious writer, Venerable of the Catholic Church, and advocate of the idea of mystical spiritual infancy. She entered the Congregation of the Sisters Handmaids of the Blessed Virgin Mary Immaculate in Stara Wieś in 1925 at the age of 22. In the 1930s, she claimed to have mystical revelations of Jesus Christ, during which she was shown a way of life based on humility and unlimited trust in God. In her