It was fortunate
that even in such fevered moments his eye was cool and quick. Something in a
shop-front went by him like a mere flash; yet he went back to look at it. The
shop was a popular greengrocer and fruiterer's. In the two most prominent
compartments were two heaps, of oranges and of nuts respectively. On the heap
of nuts lay a scrap of cardboard, on which was written in bold, blue chalk,
"Best tangerine oranges, two a penny." On the oranges was the equally
clear and exact description, "Finest Brazil nuts, 4d. a lb." M.
Valentin looked at these two placards and imagined 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 angrily 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."