The holy souls in Purgatory intercede for us, but cannot help themselves!
The following explanation and prayer (in bold type) is taken from the book, Purgatory Explained (citation at end):
“Thus far we have spoken of the different kinds of good works which we may offer to God as suffrages for the dead. It remains for us to make known an act which comprises all works and means, whereby we can most
effectually assist the poor souls; it is the heroic vow, or, as others call it, the Heroic Act of Charity towards the souls in Purgatory.
“This act consists
in ceding [giving] to them all our works of satisfaction, that is to say, the satisfactory value of all the works of our life and of all the suffrages which shall be given to us after our death, without reserving anything wherewith to discharge our
own debts. We deposit them in the hands of the Blessed Virgin, that she may distribute them, according to her good pleasure, to those souls which she desires to deliver from Purgatory.
“It is an absolute donation in favor of the souls of all that we can give them; we offer to God in their behalf all the good that we do, of what kind soever, either in thought, words or works, all that we suffer meritoriously during this life,
without excepting anything that we may reasonably give them, and adding even those suffrages which we may receive for ourselves after death.
“It must be well understood
that the matter of this holy donation is the satisfactory value of our works (see Chap. 9), and in no way the merit which has a corresponding degree of glory in Heaven; for merit is strictly personal, and cannot be transferred to another.
“Formula of the Heroic Act:
‘O Holy and Adorable Trinity,
desiring to cooperate in the deliverance of the souls in Purgatory, and to testify my devotion to the Blessed Virgin Mary, I cede and renounce in behalf of those holy souls all of the satisfactory part of my works, and all the suffrages which may be given
to me after my death, consigning them entirely into the hands of the most Blessed Virgin, that she may apply them according to her good pleasure to those souls of the faithful departed whom she desires to deliver from their sufferings. Deign, O my God, to
accept and bless this offering which I make to Thee at this moment. Amen.’
“The Sovereign Pontiffs, Benedict XIII, Pius VI, and Pius IX have approved this
heroic act, and have enriched it with indulgences and privileges, of which the principal are the following: 1. To priests who have made this act the indult of a privileged altar every day in the year. 2. The simple faithful can gain a plenary indulgence,
applicable to the holy souls in Purgatory only. 3. They may apply to the holy souls all those indulgences which are not otherwise applicable by virtue of concession, and which have been granted up to the present time, or which shall be granted in the
future. (Pius IX, Decr. 30 Sept. 1852).
“ ‘I advise all true Christians,’ says Father Mumford, ‘to cede [give] with holy disinterestedness all the fruit
of their good works which are at our disposal. I do not believe that they can make a better use of them, since they render them more meritorious and more efficacious, as well for obtaining grace from God as for expiating their own sins and shortening the term
of their Purgatory, or even of acquiring an entire exemption therefrom.’
These words express the precious advantages of the Heroic Act; and in order to dissipate all subsequent
fear which might arise in the mind, we add three remarks: 1. This act leaves us perfect liberty to pray for those souls in whom we are most interested; the application of these prayers is subject to the disposition of the adorable will of God, which
is always infinitely perfect and infinitely loving. 2. It does not oblige under pain of mortal sin, and can at any time be revoked. It may be made without using any particular formula; it suffices to have the intention, and to make it from the heart.
Nevertheless it is useful to recite the formula of offering from time to time, in order to stimulate our zeal for the relief of the holy souls by prayer, penance, and good works. 3. The Heroic Act does not subject us to the direful consequences of having
to undergo a long Purgatory ourselves; on the contrary, it allows us to rely with more assured confidence on the mercy of God in our regard, as is shown by the example of St. Gertrude.
“Venerable Denis, the Carthusian, relates that the Virgin, St. Gertrude, had made a complete donation of all of her works of satisfaction in favor of the faithful departed, without reserving anything wherewith to discharge the debts which she
herself might have contracted in the sight of God. Being at the point of death, and, like all the saints, considering with much sorrow the number of her sins on the one hand, and, on the other, remembering that she had employed all her works of satisfaction
for the expiation of the sins of others, she was afflicted, lest, having given all to others and reserved nothing for herself, her soul, on its departure from this world, should be condemned to horrible suffering. In the midst of her fears our Lord appeared
to her and consoled her, saying: ‘Be reassured, My daughter, your charity towards the departed will be no detriment to you. Know that the generous donation you have made of all your works to the holy souls has been singularly pleasing to Me; and to give
you a proof thereof, I declare to you that all the pains you would have had to endure in the other life are now remitted; moreover, in recompense for your generous charity, I will so enhance the value of the merits of your works as to give you a great increase
of glory in Heaven.’ “
[Source, pp. 264-268, Second Part, Chapter 31, Purgatory: Explained by the Lives and Legends of the Saints, by Fr. F. X. Schouppe,
S. J., Imprimatur October 11, 1893].