“Observe the fellow in mosaic.”

“The old emperor?”

“That old emperor is an exact representation of the king of hearts on all playing cards.”

“That’s right. But how does the seven of hearts open the larger safe at one time and the smaller safe at another time? And why did you open only the larger safe in the first instance? I mean on the night of 22 June.”

“Why? Because I always placed the seven of hearts in the same way. I never changed the position. But, yesterday, I observed that by reversing the card, by turning it upside down, the arrangement of the seven spots on the mosaic was changed.”

“ Parbleu! ”