Through their prayers and alms for the deceased, Christians display the relationship between this world and the world to come. The Church in this world and the Church in the other world are one and the same - one body, one in being - as does the root of a tree beneath the earth comprise one organism with the trunk and the branches of the tree above the earth. It is clear from this how we who comprise the Church on earth can receive help from the saints and the righteous ones from the Heavenly Church as well as the deceased sinners in the other world can receive help from us on earth. St. Athanasius says: "As it happens with wine inside a barrel which, when the vineyard blooms in the field, senses it and the wine itself blossoms together with it, so it is with the souls of sinners. They receive some relief from the Bloodless Sacrifice offered for them and from charity" performed for their repose. St. Ephraim the Syrian cites that same example with wine and the vineyard and concludes: "And so, when there exists such mutual sensitivity even among plants, is not the prayer and sacrifice felt even more for the departed ones?"
St. Nikolai Velimirovich
http://agapienxristou.blogspot.ca/2013/07/alms-and-prayers-for-deceased-st.html