Expression française : le serpent qui se mord la queue

What does “le serpent qui se mord la queue” mean in French?

“C’est le serpent qui se mord la queue” describes a problem that loops back on itself: A depends on B, but B needs A, so you go round and round and never break in. The classic French example — you can’t open a bank account without payslips, but you can’t get paid without a bank account. It’s the French way of saying “chicken-and-egg” or “catch-22.”

The picture is ancient: the ouroboros, a serpent or dragon curled into a circle swallowing its own tail, found in ancient Egypt and Greek and alchemical traditions as a symbol of eternal cycles and renewal. French keeps the loop but drops the mysticism, turning that endless circle into the everyday frustration of a problem that feeds itself.