What's that? There! Sparkling on the ground...
Asilver ring - thick metal twisted into an infinity loop. Lower left. See?
I bent over and picked it up. The ring was dirty, but I could see that it had words engraved all the way around it.
“Good eyes,” said M, glancing at the piece of silver in my hands. “What does it say?”
Oh, I'm serious, all right. From the Tao Te Ching, Chapter 64: