The Devotion of the First Five Saturdays as Explained by Sister Lucia
On 1 November, 1927, in a letter to Dona Maria de Miranda, her godmother, Sister Lucia wrote:

"I don't know if you already know about the reparatory devotion of the five Saturdays to the Immaculate Heart of Mary. As it is still recent, I would like to inspire you to practice it, because it is requested by Our dear Heavenly Mother and Jesus has manifested a desire that it be practiced. Also, it seems to me that you would be fortunate, dear godmother, not only to know it and to give Jesus the consolation of practicing it, but also to make it known and embraced by many other persons.

"It consists in this: During five months on the first Saturday, to receive Jesus in Communion, recite a Rosary, keep Our Lady company for fifteen minutes while meditating on the mysteries of the Rosary, and make a confession. The confession can be made a few days earlier, and if in this previous confession you have forgotten the (required) intention the following intention can be offered, provided that on the first Saturday one receives Holy Communion in a state of grace, with the intention of repairing for offenses against the Most Holy Virgin and which afflict Her Immaculate Heart.

"It seems to me, my dear godmother, that we are fortunate to be able to give Our dear Heavenly Mother this proof of love, for we know that She desires it to be offered to Her. As for myself, I avow that I am never so happy as when first Saturday arrives. Isn't it true that our greatest happiness is to belong entirely to Jesus and Mary and to love Them and Them alone, without reserve? We see this so clearly in the lives of the saints...They were happy because they loved, and we, my dear godmother, we must seek to love as they did, not only to enjoy Jesus, which is the least important -- because if we do not enjoy Him here below, we will enjoy Him up above -- but to give Jesus and Mary the consolation for being loved...and that in exchange for this love they might be able to save many souls."

The Five First Saturdays

After supper on December 10, 1925, Sister Lucia dos Santos (a postulant at that time in the Dorothean house at Pontevedra, Spain) received an apparition by the Child Jesus and the Virgin Mary in her room. Our Lady spoke to her:

"See, My daughter, My heart surrounded by thorns which ungrateful men pierce at every moment by their blasphemies and ingratitude... Say to all those who, for five months, on the first Saturday, confess, receive Holy Communion, recite the Rosary and keep Me company for 15 minutes while meditating on the fifteen mysteries of the Rosary, with the intent of making reparation to Me, I promise to assist them at the hour of death with all the graces necessary for the salvation of their souls."

Charged by Heaven's King and Queen with a new task, the young nun immediately began the work of making their requests for this new devotion known. Informing everyone of this devotion, she would later write "[You] cannot imagine how great is my joy in thinking about the consolation...that the Holy Hearts of Jesus and Mary are going to receive and of the great number of souls who are going to be saved through this amiable devotion."