The Sunday after Easter is no doubt the one Sunday in the entire liturgical year with the most names, both official and unofficial.
Just as the eighth day after Christmas (1 January) is known as the Octave Day of Christmas, so is the eighth day after Easter known as the Octave Day of Easter. An octave is “[t]he liturgical celebration of a feast for eight days—on the day itself and the seven following days” (Rev. Jovian P. Lang, OFM, Dictionary of the Liturgy (1989), p. 462). At one time, many liturgical feasts had octaves, but they were eventually suppressed except for the octaves of Christmas and Easter. The first day of Octave of Easter is Easter Sunday and the last day of the octave is the following Sunday.
In the ancient Church, the Octave of Easter was one continual feast, during which the neophytes who had received the sacraments of Christian initiation at the Easter Vigil would attend Mass and receive Holy Communion each day at a different church in Rome and attend Vespers daily at what is formally called the Major Papal, Patriarchal, and Roman Archbasilica Cathedral of the Most Holy Saviour and Saints John the Baptist and the Evangelist in Lateran, Mother and Head of All Churches in Rome and in the World. Informally, the official cathedral of the Bishop of Rome is known as Saint John Lateran or the Lateran Basilica. The newly baptized (neophytes) would also wear their white baptismal gowns throughout the entire Octave of Easter.
In what Pope Benedict XVI called the Extraordinary Form of the Roman Rite, the First Sunday after Easter is officially known in Latin as Dominica in Albis in Octava Paschæ, which can be translated literally as “Sunday in White on the Octave [day] of Easter”. It was also called Dominica in albis deponendis or “the Sunday of the laying aside of the white garments”, when the neophytes would lay aside their baptismal garments.
This Sunday is also known as Low Sunday in comparison to Easter Sunday which is the “Feast of feasts”, the “Solemnity of solemnities”, and “the supreme day of the Christian year”. Thomas Sunday is another designation, particularly in the Eastern churches. This is based on the Gospel pericope assigned for this day (John 20:19-31).
Quasimodo Sunday is another name by which the Sunday after Easter is known, coming from the first word of the Entrance Antiphon or Introit for the day’s Mass in both forms of the Roman Rite: Quasi modo géniti infántes, rationábile, sine dolo lac concupíscite, ut in eo crescátis in salútem, alleluia (Like new-born infants, you must long for the pure, spiritual milk, that in Him you may grow to salvation, alleluia).
Incidentally, this verse from 1 Peter 2:2 is where the character of “Quasimodo” from The Hunchback of Notre Dame receives his name. In Victor Hugo’s 1831 novel, the infant Quasimodo was rejected by his parents for his deformities and is abandoned at the Cathedral of Notre-Dame de Paris. Monseigneur Claude Frollo, archdeacon of the cathedral, finds the child on “Quasimodo Sunday” and “called him Quasimodo; whether it was that he chose thereby to commemorate the day when he had found him, or that he meant to mark by that name how incomplete and imperfectly molded the poor little creature was…”
Since 2000, this Sunday is officially known as Dominica secunda Paschae seu de divina Misericordia or the Second Sunday of Easter or of Divine Mercy in the Ordinary Form of the Roman Rite, and unofficially as the “Feast of Divine Mercy” for much longer than that. This is rooted in the private revelations of Saint Maria Faustina Kowalska of the Blessed Sacrament (1905-1938), a Polish religious sister and mystic, who wrote that Christ Himself desired that the first Sunday after Easter be known as the feast of Divine Mercy.
“On that day the very depths of My tender mercy are open. I pour out a whole ocean of graces upon those souls who approach the fount of My mercy. The soul that will go to Confession and receive Holy Communion shall obtain complete forgiveness of sins and punishment. On that day all the divine floodgates through which grace flow are opened. Let no soul fear to draw near to Me, even though its sins be as scarlet. My mercy is so great that no mind, be it of man or of angel, will be able to fathom it throughout all eternity” (Divine Mercy in My Soul: The Diary of Saint Faustina, n. 699).
This Sunday’s Gospel, in addition to the well-known “doubting Thomas” story, also tells of the institution of the Sacrament of Penance and Reconciliation, the Sacrament of Mercy.
“Jesus said to them again, ‘Peace be with you. As the Father has sent Me, even so I send you.’ And when He had said this, He breathed on them, and said to them, ‘Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained’” (John 20:21-23).
Regardless of what it is called, the Sunday after Easter continues the celebration of the Resurrection and serves as a reminder of the hope and joy that it brings, continuing the beginning of Easter Time or Paschaltide, a liturgical season that invites the faithful to ponder the significance of the Paschal Mystery of Jesus, “which comprises His passion, death, resurrection, and glorification, stands at the centre of the Christian faith because God’s saving plan was accomplished once for all by the redemptive death of Himself as Jesus Christ” (Compendium of the Catechism of the Catholic Church (2005), n. 112).
“The paschal mystery is the culmination of this revealing and effecting of mercy, which is able to justify man, to restore justice in the sense of that salvific order which God willed from the beginning in man, and through man, in the world” (St. John Paul II, Encyclical Letter Dives in misericordia (30 November 1980), n. 7).