When I was watching the opera “Tannhäuser” recently, I was struck by the point that the pilgrims were going to Rome for the “Gnadenfest,” the Feast of Mercy. I knew that Pope Francis had proclaimed Dec. 8 – Nov. 20 as a “Year of Mercy” and the Pope John Paul II had designated the Sunday after Easter as “Divine Mercy Sunday and I wondered what this mediæval predecessor might be. Was it Wagner’s invention, or did something of the sort actually happen? We know that pilgrimages crisscrossed Europe to various destinations: Rome, Compostela, Canterbury, and many other, less famous, shrines. But a specific Feast of Mercy at Rome was unfamiliar to me.
It all became clear when I was looking up the topic of Jubilee Years. I found an article on Wikipedia which gives a history of Jubilee Years in the Catholic Church. The article notes that although the first one which is fully documented was proclaimed by Pope Boniface VIII in 1300, it seems probable “that the proclamation of the Jubilee owed its origin to the statements of certain aged pilgrims who persuaded Boniface that great indulgences had been granted to all pilgrims in Rome about a hundred years before. It is also noteworthy that in the Chronicle of Alberic of Three Fountains, under the year 1208 (not, be it noted 1200), we find this brief entry: ‘It is said that this year was celebrated as the fiftieth year, or the year of jubilee and remission, in the Roman Court.'” So the Feast of Mercy in “Tannhäuser” wasn’t a particular day, but the Jubilee Year of 1208 — which is consistent with the timing of the action of the opera.
The original idea was to have a Jubilee Year once every hundred years, but another was held in 1350, and in 1475, a 25 year interval became the norm. This gives most people a chance to participate in one during their lifetime.
But what is a Jubilee? The Book of Leviticus, 25:8-55, prescribes a year of jubilee for the Israelites every fiftieth year. Prominent among its requirements were that all land revert to its original owner — any sale was only valid until the next jubilee. Indentures ended with the jubilee as did slavery to aliens in the land of Israel. In the Church, the concept of jubilee was transformed into one of spiritual liberation. Those who went on pilgrimage to Rome and visited the four major basilicas for a specified number of days could gain a plenary indulgence: a remission of all temporal punishment (in this life or in purgatory) for previous sins.
Pope Francis decided to proclaim an extraordinary Jubilee Year* (the next ordinary one would be in 2025) to coincide with the 50th anniversary of the conclusion of the Second Vatican Council. Prominent themes are God’s constant mercy toward his people, the Church’s proclamation of God’s mercy to all people, and our personal practice of mercy toward one another in the form of the traditionally identified corporal and spiritual works of mercy. While the Bull of Indiction proclaiming this Extraordinary Jubilee Year of Mercy (summary here) does not give specifics about the required pilgrimages and the available indulgences for participation, it is clear that the elements of pilgrimage and the granting of indulgences are part of it. To provide for the widest possible participation, there are to be places in every diocese in the world to which the pilgrimage may be made, as was the case with the Great Jubilee of the Year 2000.
*This is different from the special themes that Popes often assign to years to encourage the faithful to pay attention to those themes. We have had years of the priesthood, of consecrated life, and various elements of church life recently. I had thought until recently that the Year of Mercy was another such year. Being a Jubilee Year notably raises its significance.