The feast of the Sacred Heart of Jesus falls on the Friday nineteen days after Pentecost, following the octave of Corpus Christi. It venerates the physical heart of Christ as the symbol of his love for humanity, and belongs to a devotion that, while it has medieval roots, took its modern form in seventeenth-century France through the visions reported by the Visitation nun Margaret Mary Alacoque at Paray-le-Monial, promoted by her Jesuit director Claude de la Colombiere. The devotion's imagery, a heart crowned with thorns, wounded and aflame, became one of the most widespread in Catholic piety.
The observance spread against considerable resistance from those who thought it novel or close to worshipping a part of the body, and was extended to the whole Latin church only in the eighteenth and nineteenth centuries. It carries a strong strand of reparation, prayer offered to make amends for indifference to Christ's love, and is attached to the practice of the First Fridays. The feast has also had a public and political life, in national consecrations and in the architecture of churches such as the basilica of Montmartre in Paris.