On this Sunday every family brings its own list of names. Grandparents, parents, perhaps a child or a friend who died too soon. The Church gathers them all into one prayer before Great Lent begins. It does so with a Gospel that begins: do not be afraid, little flock.
Jesus tells a strange story. Servants wait up late for their master. When he finally comes home and finds them ready, he does not sit down to be served. He ties on an apron and serves them. That is the picture of heaven he gives us: the Lord himself at the table, caring for those who waited for him.
Our treasure is often where our grief is. The people we loved and lost hold a part of our hearts. Jesus says to keep that treasure in heaven, where it cannot be stolen. Praying for the departed is one way we do that. It keeps our hearts pointed towards the place where they are waiting, and where we hope to see them again.