"The best and most efficacious way of glorifying him (St. Michael) in Heaven and honoring him on earth is to spread devotion to the souls in Purgatory, and to make known the great mission he fulfills towards these suffering souls. It is he who is entrusted by God to lead the souls to the place of expiation and to lead them to their eternal home after purification. Each time a soul arrives to increase the number of the elect, God is glorified, and this glory in some way communicates itself also to the celestial minister. It is an honor for him to present to Our Lord the souls that will sing their thanks and His mercies through all eternity. I could never make you understand the intense love which the Heavenly Archangel has for his Divine Master, and the love which God in His turn has for St. Michael. Neither can I convey to you a true idea of the love and pity St. Michael has for us. He encourages us in our sufferings by speaking to us of Heaven.
Tell the Father that if he wishes to please St. Michael, he will most earnestly recommend devotion to the souls in Purgatory. People in the world do not think of it. When they have lost their relatives or friends, they say a few prayers, weep for a few days and that is the end of it. The souls are henceforth abandoned. It is true that they merit this, for while they were on earth they neglected the dead. The Divine Judge deals with us in this world according to our actions in the former. Those who have forgotten the holy souls are forgotten in their turn. This is only fair. Perhaps if they had been reminded to pray for the dead and had been told a little about Purgatory, they might have acted differently."
(Revelation of a Nun Soul in Purgatory to a Nun on Earth)