description, "Finest Brazil nuts, 4d. a lb." M. Valentin looked
at these two placards and fancied he had met this highly subtle
form of humour before, and that somewhat recently. He drew the
attention of the red-faced fruiterer, who was looking rather
sullenly up and down the street, to this inaccuracy in his
advertisements. The fruiterer said nothing, but sharply put each
card into its proper place. The detective, leaning elegantly on
his walking-cane, continued to scrutinise the shop. At last he
said, "Pray excuse my apparent irrelevance, my good sir, but I
should like to ask you a question in experimental psychology and
the association of ideas."

The red-faced shopman regarded him with an eye of menace; but
he continued gaily, swinging his cane, "Why," he pursued, "why are
two tickets wrongly placed in a greengrocer's shop like a shovel
hat that has come to London for a holiday? Or, in case I do not
make myself clear, what is the mystical association which connects
the idea of nuts marked as oranges with the idea of two clergymen,
one tall and the other short?"

The eyes of the tradesman stood out of his head like a
snail's; he really seemed for an instant likely to fling himself
upon the stranger. At last he stammered angrily: "I don't know
what you 'ave to do with it, but if you're one of their friends,
you can tell 'em from me that I'll knock their silly 'eads off,
parsons or no parsons, if they upset my apples again."

"Indeed?" asked the detective, with great sympathy. "Did they
upset your apples?"