The Adventures of Sherlock Holmes
"It is simplicity itself," said [Holmes]; "my eyes tell me that on the inside of your left shoe, just where the firelight strikes it, the leather is scored by six almost parallel cuts. Obviously they have been caused by someone who has very carelessly scraped round the edges of the sole in order to remove crusted mud from it. Hence, you see, my double deduction that you had been out in vile weather, and that you had a particularly malignant boot-slitting specimen of the London slavey." […]
I could not help laughing at the ease with which he explained his process of deduction. "When I hear you give your reasons," I remarked, "the thing always appears to me to be so ridiculously simple that I could easily do it myself, though at each successive instance of your reasoning I am baffled until you explain your process. And yet I believe that my eyes are as good as yours" (Bohemia.1.12-13).
"Well, but China?"
"The fish that you have tattooed immediately above your right wrist could only have been done in China. I have made a small study of tattoo marks and have even contributed to the literature of the subject. That trick of staining the fishes' scales of a delicate pink is quite peculiar to China. When, in addition, I see a Chinese coin hanging from your watch-chain, the matter becomes even more simple."
Mr. Jabez Wilson laughed heavily. "Well, I never!" said he. "I thought at first that you had done something clever, but I see that there was nothing in it after all."
"I begin to think, Watson," said Holmes, "that I make a mistake in explaining. 'Omne ignotum pro magnifico,' you know, and my poor little reputation, such as it is, will suffer shipwreck if I am so candid" (League.23-6)
Indeed, I have found that it is usually in unimportant matters that there is a field for the observation, and for the quick analysis of cause and effect which gives the charm to an investigation. The larger crimes are apt to be the simpler, for the bigger the crime the more obvious, as a rule, is the motive. In these cases, save for one rather intricate matter which has been referred to me from Marseilles, there is nothing which presents any features of interest (Identity.11).