A pious devotional exercise consisting of mental and vocal prayer with exposition of the Blessed Sacrament. It draws its inspiration from Christ's words to the Apostles in Gethsemane: "Can you not watch one hour with me?" It was taught by the Savior to St. Margaret Mary (1647-90) as one of the special practices of the Sacred Heart devotion. In the early nineteenth century a confraternity was founded at Parayle-Monial, France, to spread the devotion, which has been highly recommended by the popes. If the hour is made publicly it is designated by a priest or the director; if made privately, any hour is suitable but preferably Thursday or Friday evening. The Passion of Christ is the theme during the hour, variously divided into meditation, vocal prayer, and singing. Many religious communities include, the devotion as part of the horarium of their day.