Celebrations are mysterious things. On one level they are simple: People gather, eat food, drink wine, maybe dance and give speeches. Then it’s over.
But a celebration is never really over, and that is the mystery part. A good celebration marks a moment when a particular group of people were connected, when they formed themselves into a kind of collective tribe.
Decades later you can still easily recall some celebrations. You still feel connected to people you met there, even if they have long departed from this Earth.
I suspect that there is something deep in the evolution of humans that privileges celebrations. As lighthearted as they may seem on the surface, they help us to form and to affirm the powerful ties that bind us together. They may be one of the reasons that our species has survived so spectacularly well.