The Agnus Dei is not only a part of the mass often chanted, it is also a term for the small wax medallions which portray, on one side, the Easter lamb. The other side shows a given saint.
They had a special significance for the Cistercians of Santa Croce in Gerusalemme, a famous abbey in Rome, because they had been given the privilege of preparing the wax molds in a delicate and intricate process. The wax was infused with holy oil. The week after Easter, the pope would bless the Agnus Dei medallions, but not every year, only in the first and seventh years of his pontificate. They were then distributed to the faithful. A similar practice (distributing pieces of the Easter candle) was also known in the first centuries of Christendom.
Here is a video of the pope surrounded by Cistercians in 1959.

The Cistercian dimension begins in 1599, so reports Chiaravalle's homepage, when the "Foglianti" Cistercians in San Bernardo alle Terme in Rome obtained from Pope Clement VIII "an exclusive and perpetual commission" to produce the Agnus Dei. The Feuillants were disbanded in 1802 and aggregated with the Cistercian Congregation of St. Bernard in Italy, and the privilege passed to Santa Croce in Gerusalemme.

O schwere Gottes Hand, wie bist allhie zu Land so schmerzlich zu gedulden: Ach wie muß man so theur, in disem strengen Feuer, bezahlen alle  Schulden. Hätt ich mir die Pein zuvorgebildet ein, die man allhie muß leiden; so hätt ich also sehr gewißlich nimmermehr getracht nach schnöden Freuden.
Lebhafte Vorstellungen vom Fegefeuer, wie die oben zitierten Zeilen aus einem Augsburger Lied ca. 1690, sind von tiefster kulturprägender Bedeutung für das europäische Abendland vom Mittelalter bis in das 20. Jh. Klöster wurden zu einem großen Teil von Spenden finanziert, die bezahlt wurden, um die Pein der Seelen im Fegefuer zu lindern bzw. zu beenden. Das Mittel dazu war fürbittendes Gebet, vor allem in der Hl. Messe. 
Der obige Textausschnitt ist deswegen eine wertvolle Quelle, weil die Augsburger Lyrik zeitgenössische Vorstellugen vom Purgatorium liefert und uns ein zuverlässiges Bild von jenen Gefühlen machen lässt, die in der Betrachtungswelt der Geldgeber herrschten. Das Lied hilft, die seelsiche Motivation hinter den Seelgerätsstiftungen, die wir heute etwas nüchterner Messintentionen nennen, besser zu verstehen. 

Fr. Luke was the last monk of St. Mary's Monastery in New Ringgold, Pennsylvania (Diocese of Allentown). Google reviews claim that the "beautiful old monastery" has long been up for sale: "It has 17 bedrooms and a beautiful chapel on 12 1/2 acres." Fr. Luke was Prior and co-founder of St. Mary's, where four formerly Trappist monks had started anew around 1975. They had had differences of opinion about observance and liturgy at St. Joseph's Abbey in Spencer, Massachusetts. Anderson had made his solemn profession in Spencer in 1953 and was ordained to the priesthood the year thereafter. 
The community at St. Mary's transferred to the Common Observance and attained the status of a priory of the Cistercian Order. They earned their livelihood first by making computer punch cards (long before the PC!). Later, they became tailors, making pants. Over the years, more than a dozen novices had entered St. Mary's, but none stayed. 
Fr. Luke passed away on 4 January 2025 at the age of 97, the last of the four founding confreres. Alfred Schlert, Bishop of Allentown, officiated at the requiem.
Anderson wrote a thesis at the Angelicum titled The concept of truth in the philosophy of William James (1965). He also had a master's degree from Princeton University. He served on the editorial board of the Cistercian Fathers Series from ca. 1970 and was also an editor of what was supposed to be the English translation of Bernard's collected works (a joint initiative of Cistercian Publications and Consortium Press in the early 1970s). He contributed "The Rhetorical Epistemology in Saint Bernard's Super Cantica" to the acclaimed collection titled Bernardus Magister in 1992. In 2005, he published The Image and Likeness of God in Bernard of Clairvaux's Free Choice and Grace, which he dedicated to St. Teresa of Calcutta, with whom he had worked on several occasions, holding workshops and giving retreats for the Missionaries of Charity. His retreats and conferences were especially popular; he was a regular retreat master at numerous monasteries and held countless university lectures.