Keep in mind that prayer for the reposed is strong through its communality, in that it comes from the entire Church. The Church breathes prayer.
In nature, when a pregnant mother breathes, the strength she receives from this breath passes on to her child. So also in a Grace-filled way the Church breathes a prayer that is shared by all, and the power of the prayer passes on to the reposed, who are held in the bosom of the Church, which is made up of the living and the dead, the militant and the triumphant.
Do not be slothful, but zealously commemorate all of our departed fathers and brothers whenever you pray. It will be your alms for them. - St. Theophan the Recluse