“Yes, yes,” said the attendant excitedly, and pointed at the dark splash on the white paper; “threw it over there on the wall.” Valentin looked his query at the proprietor, who came to his rescue with fuller reports. “Yes, sir,” he said, “it’s quite true, though I don’t suppose it has anything to do with the sugar and salt. Two clergymen came in and drank soup here very early, as soon as the shutters were taken down. They were both very quiet, respectable people; one of them paid the bill and went out; the other, who seemed a slower coach altogether, was some minutes longer getting his things together. But he went at last. Only, the instant before he stepped into the street he deliberately picked up his cup, which he had only half emptied, and threw the soup slap on the wall. I was in the back room myself, and so was the waiter; so I could only rush out in time to find the wall splashed and the shop empty. It don’t do any particular damage, but it was confounded cheek; and I tried to catch the men in the street. They were too far off though; I only noticed they went round the next corner into Carstairs Street.” The detective was on his feet, hat settled and stick in hand. He had already decided that in the universal darkness of his mind he could only follow the first odd finger that pointed; and this finger was odd enough. Paying his bill and clashing the glass doors behind him, he was soon swinging round into the other street. 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, an array of goods set out in the open air and plainly ticketed with their names and prices. 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 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.”