“Today, we engage in a practice that St. John Chrysostom reported had been ordered by the Apostles: praying for the dead. The feast of All Souls has a particular ring to each person though — if yesterday’s feast of All Saints failed to remind you of your final end and where you ought to strive to be, today is here to remind you that someday it will be your soul in the pile of names prayed for today. Today is the beginning of the season of the year when the Church emphasizes to you that you are to remember your final end. You, me, and everyone else who reads this will die, face judgment, and be admitted to Heaven or Hell. It’s that first part — that we all die due to original sin, that everyone forgets — or buries. But remembering your death is a key to a clean heart. Eventually, you will face the Just Judge. Everyone else who has already died already has. By praying for them, you remember your own appointment to be there someday, too…”
https://bellarmineforum.org/all-souls-day-one-key-to-a-clean-heart-the-beginning-of-memento-mori/