... non licet bovi.
It is a Latin phrase, literally "What is permissible for Jove is not permissible for a bull" is often translated as "Gods may do what cattle may not".
But you may read this as a memento mori, too.
I really like the symbolism. That scythe is as important and universal to Western Civilization as the Crucifix.Yep, exactly ... and nevertheless there is so much more "behind the scene" ... fascinating.