History of the Feast of Divine Mercy

When Jesus revealed the Sacred Image of Himself as the Divine Mercy to Sister Faustina Kowalska on February 22, 1931, he declared:

I desire that there be a Feast of Mercy. I want this image, which you will paint with
a brush, to be solemnly blessed on the first Sunday after Easter; that Sunday is to
be the Feast of Mercy
(Diary, 49).

One day, as Sister Faustina was offering all her prayers and sufferings so that this feast would be established as Our Lord desired, she said to Him: “They tell me that there is already such a feast and so why shuld I talk about it?” Jesus answered:

And who knows anything about this feast? No one! Even those who should be proclaiming My mercy and teaching people about
it often do not know about it themselves. That is why I want the image to be
solemnly blessed on the first Sunday after Easter, and I want it to be venerated
publicly so that every soul may know about it. Make a novena for the Holy Father’s
intention. It should consist of thirty-three acts; that is, repetition that many times
of the short prayer-which I have taught you-to The Divine Mercy
(Diary, 341).

These words, I believe, help us to understand what Sister Faustina wrote for her spriritual director: “There will come a time when this work … will be as though utterly undone. And then God will act with great power, which will give evidence of its authenticity. It will be a new splendor for the Church, although it has been dormant in it from long ago” (Diary, 378).
“Dormant!” That means “not active … in a state of suspension … sleeping!” And “new splendor” can surely mean “a new awakening.” The spontaneity with which the celebration of the Feast of Mercy is observed throughout the world today certainly attests to the truth of Sister Faustina’s prophecy.
The idea of this special celebreation of God’s mercy on the Sunday after Easter is not a new or radical idea stemming simply from private revelation. Our Lord, through Sister Faustina, is simply reemphasizing what was strongly urged by St. Thomas the Apostle in the earliest liturgical document in esixtence, the “Apostolic Constitutions.” There we read:
“After eight days [following the Feast of Easter] let there be another feast observed with honor, the eight day itself, on which He gave me, Thomas, who was hard of belief, full assurance, by showing me the print of the nails and the wound made in His side by the spear.”
One of the greatest Doctors of the Church, St. Gregory of Nazianzen, also supports this feast, declaring that the Octave-Day of Easter is even a greater feast than Easter – though it takes nothing whatever away from the greatness of the Day of the Resurrection itself. Easter Sunday is the boundary between death and life (a creation). But its eigth day, the Octave, is the fulfillment of what Easter is all about – perfect life in the eternity (a second creation, more admirable and more sublime than the first).
Saint Gregory’s reasoning is very much in keeping withthe teaching of St. Thomas Aquinas who, following Aristotle, distinguishes a two-fold perfection: “The first looks to the essence of the thing,” he writes, “the second to tis operation; and this second perfection is greater than the first.”
If, as St. Thomas teaches, creation is the first great manifestation of God’s mercy, then the attainment of the purpose of creation – eternal life in its fullness – is an even greater gift of mercy.
Easter Sunday represents our creation in the life of Grace through fith in the Risen Savior. The Octave Sunday of Easter represents the fulfillment of that “creation in grace.” Thus it is, as St. Augustine says, “the most priviliged octaveday” and certainly merits the title Feast of The Divine Mercy.