“The train of reasoning is not very obscure, Watson,” said Holmes with a mischievous twinkle. “It belongs to the same elementary class of deduction which I should illustrate if I were to ask you who shared your cab in your drive this morning.”

“I don’t admit that a fresh illustration is an explanation,” said I with some asperity.

“Bravo, Watson! A very dignified and logical remonstrance. Let me see, what were the points? Take the last one first⁠—the cab. You observe that you have some splashes on the left sleeve and shoulder of your coat. Had you sat in the centre of a hansom you would probably have had no splashes, and if you had they would certainly have been symmetrical. Therefore it is clear that you sat at the side. Therefore it is equally clear that you had a companion.”

“That is very evident.”

“Absurdly commonplace, is it not?”

“But the boots and the bath?”