On 31 August 1670, the first feast of the Sacred Heart Mass was celebrated at the Grand Seminary of Rennes. With this Mass, the devotion of the Sacred Heart of Jesus became a public devotion for the whole Catholic Church.
St. John Eudes had played a key role in spreading devotion to the Sacred Heart of Jesus. Though the devotion can be traced to the earlier writings of Sts. Bernard of Clairvaux, Bonaventure and Gertude and the Church Fathers. A key theme for the celebration of the Feast of the Sacred Heart would be the love of Jesus for all humanity.
In 1856, Pope Pius IX will make celebration of the Feast of the Sacred Heart obligatory. Pius XII would raise the Feast to the status of a Solemnity. The Feast of the Sacred Heart has become particularly linked to the priesthood and the recent Year of the Priest began on the Solemnity of the Sacred Heart.