Here is the very clear explanation of this devotion as presented on the website of the Archconfraternity of the Holy Rosary (a ministry of the Dominican Order):
Devotion of the Five First Saturdays
The following is an explanation of the conditions contained in Our Lady’s request regarding the Communion of reparation on the First Saturdays of the Month.
1. Confess and receive Holy Communion
On February 15, 1926 the Child Jesus alone came to visit Sr. Lucia and asked if the devotion to the Immaculate Heart of Mary was being propagated. Sr. Lucia spoke of a difficulty some people have in confessing on the first Saturday, and asked if they might be allowed eight days in order to fulfill Our Lady’s requests. Jesus answered: “Yes, even more time still, as long as they receive Me in the state of grace and have the intention of making reparation to the Immaculate Heart of Mary.”
2. Recite the Rosary
Five decades of the Rosary may be recited at any time or place; yet, since one will be attending Mass in order to receive Holy Communion, a very desirable time and place would be before or after Mass in the presence of the Blessed Sacrament. Meditation on the mysteries according to one’s capacity is an essential condition for praying the Rosary. Yet, involuntary distractions do not rob the Rosary of fruit if one is doing the best he can.
3.”Keep me company for fifteen minutes while meditating on the mysteries of the Rosary.”
The question is often asked: Does the meditation while reciting the Rosary fulfill this condition, or is there required an additional fifteen minutes of meditation? That an additional 15 minutes of meditation is required was recently confirmed by Sr. Lucia of Fatima. It is clear too from a statement by the first Bishop of Fatima.
The last entry in the chronology of Fatima, published in the official Calendar of the Sanctuary for the year of 1940, and signed by Dom Jose Correia da Silva, the first Bishop of Fatima, gave a summary of Our Lady’s requests concerning the Five First Saturdays. From that official statement in the Calendar of the Sanctuary, we read the Bishop’s enumeration of the various items that pertain to the devotion of the five Saturdays:
It consists in going to Confession, receiving Communion, reciting five decades of the Rosary and meditating for a quarter of an hour on the mysteries of the Rosary on the first Saturday of five consecutive months. The Confession may be made during the eight days preceding or following the first Saturday of each month, provided that Holy Communion be received in the state of grace. Should one forget to form the intention of making reparation to the Immaculate Heart of Mary, it may be formed at the next Confession, occasion to go to confession being taken at the first opportunity.
The meditation embraces one or more mysteries; it may even include all, taken together or separately, according to individual attraction or devotion; but it is preferable to meditate on one mystery each month.
Speaking of the requirement of “keeping me company for fifteen minutes while meditating on the mysteries of the Rosary,” the Bishop’s comment that “it is preferable to meditate on one mystery each month” could apply only to an extra fifteen minutes, for each decade of the Rosary must have its own particular meditation. This is clear from the definition of the Rosary given in the official document of the Church on indulgences, the ENCHIRIDION OF INDULGENCES published by Pope Paul VI in 1968. It describes the Rosary as follows:
“The Rosary is a certain formula of prayer, which is made up of fifteen decades of HAIL MARYS with an OUR FATHER before each decade, and in which the recitation of each decade is accompanied by pious meditation on a particular mystery of our Redemption.” (n. 48)
Like the Rosary, this meditation may be made any time or place during the first Saturday. Yet again, like the Rosary, a very fitting time and place would be in the presence of the Blessed Sacrament before or after Mass. The question has been asked: “Would an extra Rosary, which would require about fifteen minutes, fulfill this request? It would seem, if fruitfully meditated, that it would. Or again, the time could be spent reading meditatively on one of the fifteen mysteries, which is a form of mental prayer that involves reading with frequent pauses to reflect on the matter read.
4. With the intention of making reparation.
All of the conditions mentioned above – in numbers 1 to 3 – should be fulfilled with the intention of making reparation to the Immaculate Heart of Mary. On the occasion of the visit of the Child Jesus to Sr. Lucia (Feb. 16, 1926), she asked: “My Jesus, what about those who forget to make the intention?” Jesus answered: “They can do so at their next confession, taking advantage of their first opportunity to go to Confession.”
The above are the minimum requirements for fulfilling the conditions of Our Lady’s promise to obtain for us “at the hour of death the graces necessary for salvation.” Yet, these Communions of reparation, as has been pointed out, are only a portion of the devotion of the Immaculate Heart of Mary. These few pages are meant to help bring about a frame of mind and heart that will make us aware of the need of reparation all through the month, and not just on the first Saturday.
Why Five Saturdays?
It is sometimes asked why Our Lady asked for Communions of reparation on five first Saturdays, instead of some other number. Our Blessed Lord answered that question when He appeared to Sr. Lucia May 29, 1930. He explained that it was because of five kinds of offenses and blasphemies against the Immaculate Heart of Mary, namely: blasphemies against her Immaculate Conception, against her perpetual virginity, against the divine and spiritual maternity of Mary, blasphemies involving the rejection and dishonoring of her images, and the neglect of implanting in the hearts of children a knowledge and love of this Immaculate Mother.
Now, even though it does talk here about the “five” First Saturday’s (traditionally these being of January, February, March, April, and fittingly ending in May) many devotees of our Lady will keep the First Saturday Devotion year round just as they do with the First Fridays. The latter, however, does not have to be made on any particular First Fridays, but simply need to be nine consecutive First Fridays.
Practicing the First Saturdays devotion is a very important part of living the message of Fatima, and it is the living of this message to which has been attributed some of the most incredible miracles of divine protection ever recorded. Let us look just at two examples.
On August 6th, 1945 the first atomic bomb was dropped on Hiroshima Japan. Never before had the outright slaughter of innocent civilians by the tens of thousands been seen to be acceptable in a civilized society. But President Truman, a Freemason, was confident that morals simply were lagging behind technology and that one day we would look back on this terrible event and see it as perfectly noble.
What was amazing was not what happened, but rather what didn’t happen. Just eight blocks from ground zero stood the Jesuit Church of Our Lady of the Assumption. Not only was the church still standing, but the priests inside were all perfectly unharmed and more than that were never shown to have suffered any effects of radiation whatsoever.
Over the next 30 years, Father Hubert Schiffer (the Superior of the house) was examined about 200 times for radiation exposure, and the doctors were unable to find any at all. These four Jesuit Priests survived a nuclear blast that killed almost all other people even at over ten times the distance from the blast. Almost every other person, even at 3 times the distance from the explosion, died instantly. Those within a radius ten times the distance at which the Jesuits were exposed, died from radiation poisoning within days. Half a million people were annihilated.
All four members of the small Jesuit community escaped alive when most of the City of Hiroshima was obliterated. Nine days later, on the Feast Day of the Assumption of the Blessed Virgin Mary into Heaven, Wednesday August 15 1945, the military of the United States in that region were ordered to cease fire. From a pool of survivors of a fifteen-kilometer radius, the Jesuits were the only people who, after fifteen years, were still alive. All the rest had died due to radiation exposure. When asked what obtained this incredible miracle the Jesuits emphatically responded:
We believe that we survived because we were living the Message of Fatima. We lived and prayed the Rosary daily in that Rectory.
On August 9th the second bomb was dropped on Nagasaki. This city was a Catholic center in Japan and more than ten thousands Catholics were killed by this bomb. Here too though was an incredible miracle in another religious house. This one had been personally established by Saint Maximilian Kolbe, and had been placed in a location specifically indicated to him by our Lord. This Friary was also completely unharmed by this bomb, and again the Franciscans attributed their deliverance to the fact that they lived the message of Fatima as a community.
If then our Lady will protect her devotees from even a direct nuclear blast what have we to fear?! Let us throw ourselves into the arms of Mary and snuggle close to her Immaculate Heart which can only and inevitably draw us into a perfect union with the most Sacred Heart of her Son Jesus.
Sermon: Make Reparation to the Immaculate Heart (5:06)
Sermon: First Saturday Devotions (5:04)
Sermon: Fatima: The Vision of Hell, the Torments of the Damned in Hell (29:01)