Though this feast has medieval origins, it wasn't added to the universal calendar until 1814, and wasn't moved to this day until 1913.
Traditionally, the seven sorrows are:
•at the prophecy of Simeon;
•at the flight into Egypt;
•having lost the Holy Child at Jerusalem;
•meeting Jesus on his way to Calvary;
•standing at the foot of the Cross;
•Jesus being taken from the Cross;
•at the burial of Christ.
At today's Mass, the sequence is the famous Stabat Mater: