The Feast of the Sacred Heart (properly the Solemnity of the Sacred Heart or the Feast of the Most Sacred Heart of Jesus) is a feast in the liturgical calendar of the Roman Catholic Church. It falls 19 days after Pentecost, on a Friday. The earliest possible date is 29 May, as in 1818 and 2285. The latest possible date is 2 July, as in 1943 and 2038.
But the first liturgical feast of the Sacred Heart was celebrated, with episcopal approval, on 31 August 1670, in the major seminary of Rennes, France, through the efforts of John Eudes. The Mass and Office composed by this saint were adopted elsewhere also, especially in connection with the spread of devotion to the Sacred Heart following on the revelations of Margaret Mary Alacoque. A Mass of the Sacred Heart won papal approval for use in Poland and Portugal in 1765, and another was approved for Venice, Austria and Spain in 1788. Finally, in 1856, Pope Pius IX established the Feast of the Sacred Heart as obligatory for the whole Church, to be celebrated on the Friday after the Octave of Corpus Christi.
The Mass prayers and readings approved on that occasion were replaced with new texts in 1929, and the Roman Missal published in 1970 provided three sets of prayers and readings, one for each year of the three-year liturgical cycle.
The Mass, which is celebrated with white vestments, may be used as a Votive Mass on other days also, especially on the first Friday of each month.
Since 2002, the Solemnity of the Sacred Heart of Jesus is also a special Day of Prayer for the Sanctification of Priests.
In 2009, the feast marked the beginning of a "Year for Priests".
Traditional Latin Mass filmed on the Feast of the Sacred Heart in the small chapel of the International Seminary of Saint Cure d'Ars, Flavigny, France, in 1999. The seminary is the Society of Saint Pius X's second European seminary. Typically seminarians spend their first year of spiritually there before leaving for Ecône, Switzerland, to complete their training.The film presents the ceremonies of the Missa Solemnis or Solemn High Mass with Gregorian chant and polyphonic motets. Some local customs take place during the Mass. For example, birettas are not worn and the Domini Non Sum Dignus is recited aloud by all present. More astute listeners might also notice the French pronunciation, which is perhaps not the ideal..