“Do you remember one of Holmes's little scores over Watson about the number of steps up to the Baker Street lodging? Poor old Watson had been up and down them a thousand times, but he had never thought of counting them, whereas Holmes had counted them as a matter of course, and knew that there were seventeen. And that was supposed to be the difference between observation and non-observation. Watson was crushed again, and Holmes appeared to him more amazing than ever. Now, it always seemed to me that in that matter Holmes was the ass, and Watson the sensible person. What on earth is the point of keeping in your head an unnecessary fact like that?”