In my years of working with Sherlock Holmes, I had never seen him so devitalized. I encountered him in our sitting room at 221B Baker Street draped over his favorite chair, slumping so deeply that the front edge of the cushion barely met his posterior. With his legs straight as a plank, his shoes stretched out to near the fireplace coals.

“The greatest mystery,” he said languidly, “is the human mind. I am biased in that I treat my brain as a thinking machine. That metaphor does not extend to the fellow members of my species. Is the human skull no more than a bowl of chemical soup with alphabetti pasta as its language? Is humankind held sway to the humors of unfathomable passions?”

“What brought about these musings?” I asked. Having returned from a house call, I set down my medical bag and took off my gloves.

“My dear Watson, I have spent the last three days as a spectator in the gallery of an inquest. I had read about the crime in the dailies and it seemed such a puzzle as to motive, I decided to visit the hearings to gain some sense of it.

“Connor Grant, a schoolmaster, taught English literature at the exclusive St. Clementine’s Public Schools for Girls. By all accounts he was competent and conscientious. His students loved him. Wednesday last, he visited Wexner and Wexner’s, an upscale pawnbroker in the Hatton Gardens District. He wore a pillowcase over his head as a mask and carried a revolver. He demanded the money from the cashier’s till. Both proprietors testified to the fact that Ivan Wexner, one of the brothers, took out a shotgun and shot the would-be robber in the chest. Grant died immediately. His gun proved to be unloaded. And there you have the story from the papers. The inquest added nothing more to the puzzle of the man’s motive, only to have many of his students provide testimonials as to what a wonderful teacher Mr. Grant was, as though that would provide further enlightenment.”

“Was he desperate for money?”

“No signs of gambling, mismanaged finances, or debt. He may have been unsatisfied with his income, we cannot know. Nevertheless, St. Clementine’s provided room and board and an adequate salary. Furthermore, Wexner’s was not the sort of establishment to be flush with money. They had a mere sixty-five pounds in their till, hardly enough to risk one’s career and life. Perhaps he would have gone on to ask for jewels. There was nothing to suggest that Grant had tried such an audacious act before. Watson, if human motives cannot be divined, then crimes become random affairs, and my investigations futile.”

I realized Holmes and I had reversed our usual roles. He was expounding a mystery rather than providing the sharp observations that would solve one.

“I went to the inquest for answers,” he continued. “I can usually see through a criminal’s veneer, pick apart inconsistencies and uncover the unsavory truths beneath. Was he a thrill-seeker? A Mr. Hyde? I found no answers. The only one who can speak to motive was Connor Grant and he is dead.”

I regularly treat melancholia: physical disease oft dispirits a patient. My recommendation is always the same: action. “My good friend, you need to hire yourself as a client and investigate this affair.”

He drew up his legs and scooted back so that he sat fully upright. A smile broke across his face along with an expression I seldom witnessed in him: modesty. “Ah, my good doctor! What a marvelous proposal! You have grappled this matter better than I. At the inquest I could not ask questions. I was as passive as a bench, allowing myself to be persuaded by the case’s seeming abstruseness. Come with me, my friend. Humankind is our client, the most inscrutable we’ve ever had, and we must make sense of it!”

A formidable proposition.

Holmes instructed the hansom driver to take us to St. Clementine’s School for Girls in Charing Cross. “Watson, my gloomy fit transformed me into a fool. I stated that the only one who could prove the motive is dead. A specious conclusion. It is possible that those who knew what incited him did not wish to speak ill of the dead.”

“Quite reasonable,” I said. “And I suspect that we can visit his living quarters to search for a journal, or perhaps, a suicide note.”