We present this small treatise to pious persons, entreating them to peruse it. Long ago the Holy Ghost said: "It is a holy and wholesome thing to pray for the dead, that they may be loosed from their sins." (II Macabees 12:46) Our Lord shed tears in seeing the tomb of Lazarus, and the Church, well acquainted with the feelings of her Divine Founder, is incessently recommending charity for the Souls suffering in Purgatory. One of her eminent doctors, St. Thomas of Aquinas, has said that: "Of all prayers, the most meritorious, the most acceptable to God are prayers for the dead, because they imply all the works of charity, both corporal and spiritual." But there are many people unconscious of the fact that charity for the "Poor Souls" is profitable to the living as well as to the dead. It is the teaching of the most learned theologians, viz: St. Alphonsus Ligori, Sylvius, Robert Bellarmine, Bonacina, and Suarez. "It is true," says St. Alphonsus, "they are unable to pray or merit anything for themselves, yet, when they pray for others, they are heard by God." Let us refer to Bellarmine: "The Souls in Purgatory," says he, "can pray for those, who address to them their petitions, and obtain from God help, forgiveness, assistance against temptations, and, all favors, both temporal and spiritual, which they may need." Many Saints have experienced this wonderful assistance. St. Catherine of Bologna assured her Sisters that: "She obtained many favors by the prayers of the holy Souls in Purgatory, which she had asked in vain, through the intercession of the Saints." St. Theresa affirms that: "She always obtained the favors which she asked from God, through the intercession of the Poor Souls." We read also in the book of St. Bridget's Revelations that: "Being one day conducted by an Angel into Purgatory, she heard a soul say: "Oh Lord, vouchsafe to reward those who assist us! Return hundredfold blessings to those who help us and introduce us into the light of Heaven." St. Leonard of Port Maurice emphatically affirms that: "The blessed Souls, delivered by our prayers, will come down from Heaven to assist us in our temporal and spiritual affairs." The Venerable Cure d' Ars, replying to a priest said: "If one knew what we may obtain from God by the intercession of the Poor Souls, they would not be so much abandoned. Let us pray a great deal for them, they will pray for us." Blessed Margaret Mary Alacoque had a special devotion for the Souls in Purgatory and has often accepted the charge of suffering for them. "Would that you knew," she said, "how my soul was replenished with joy, when speaking to those Souls, and seeing them immersed in glory as in a deep ocean. As I requested them to pray for you, they replied: "An ungrateful soul is not to be found in Heaven!" No, we cannot be deceived! If we have an ardent charity, a sincere piety, a true devotedness for the Poor Souls, we will be favored with their protection. Let us try it! When we are in trouble, when we long for a favor, let us perform some pious or charitable work for the relief of the "Poor Souls." They will be grateful, they will plead for us, and present our requests to the Eternal Father, Who loves them. May God bless this humble work! May He deign to enkindle generous hearts with zeal for the "Poor Souls." "Blessed are the merciful: for they shall obtain mercy." (Matt., V., 7.)