the "great apparition," on 16th June 1675, Christ asked St. Margaret Mary to request that the Feast of the Sacred Heart be celebrated on the Friday after the eighth day of the Feast of Corpus Christi.
The feast was meant to atone for the ingratitude of men for the sacrifice that Christ had made for them.
The Sacred Heart of Jesus represents both His physical heart and His love for all mankind.
The feast became popular after St. Margaret Mary's death in 1690. However, the Catholic Church had some doubts about St. Margaret Mary's visions.
The feast was only celebrated officially in France since 1765.
In 1856, Pope Pius IX, at the request of the French bishops, decided that the feast should be celebrated by the universal Church.