Holmes was far less particular about his sleep than I. He kept irregular hours. I was the one with the medical practice (admittedly, one more feeble than even my least-thriving patients). A visitor so late on a Saturday evening troubled him not at all.

Mrs. Hudson, our landlady, left him in our care with an indignant slam of the door behind her.

Holmes and I had both quickly donned robes. His own, which had a dark red oriental pattern, hardly seemed different from the tattered dressing gown he sported by day. Ignoring our visitor for the moment, he married a pipe to a plug of tobacco. “I say, Watson, there’s no need for you to put yourself out.”

Sitting down in my own chair, I shrugged. “I am up from my bed,” I replied. “Might do well to see what is the matter.”

Our visitor, to his credit, was mortified. “I beg your pardons, gentlemen, both of you! Were it not for the urgency of the matter, I would never have troubled you so.”

He was a thin man, still wrapped in a heavy coat, and with a broad-brimmed hat leaving little more than a pair of spectacles and a bushy beard which disappeared under the collar of his coat.

Holmes gestured for our visitor to sit. He took a babe’s succor in the mother’s-milk of his tobacco. Then, tilting his head to one side to waken his sleeping neck muscles, he said:

“Think nothing of it, old man. I don’t believe that anti-Semitic riots are going to convulse London tomorrow morning simply because a few old society dames feel that a Jewish diamond merchant has rooked them on the price a bit. However, I know the sad history of intolerance your people have suffered, and whatever I can do to allay your fears I will do—which includes running to ground the blackguards whom you feel have been dumping diamonds of suspect provenance upon the market.”

Our visitor jumped as though charged with an electrical battery.

“How—how did you know?”

Holmes smiled his usual cat’s smile—actually, having recently read a childrens’ book left behind by one of my patients, a Mrs. Liddell, I would call it a ‘Cheshire Cat’s-smile’—and waved a hand to put the man at ease.

Our visitor took off his large hat to reveal a mostly bald head, upon which was perched a small, round cloth cap—the ‘yarmulke’ of observant Hebraic men.

“Simple observation and deduction, backed by a well of knowledge accumulated over a lifetime,” said Holmes. “You came to visit us in the dead of night, long after my publicly-known business hours had ended. Why? Because you were desperate. So, I know it is an urgent matter. You could have just jumped off a ship from a foreign port, true, and therefore this was the first moment you had to make your way to my offices; that has happened to me before when I have been rousted at night. But your dress is common local clothing for our weather, including your Saville Row boots and your domestic raincoat, nor do you have a trace of a foreign accent. You live in London and traveled some short distance. You could have, therefore, visited me during the day. Why not?”

“I beg you to forgive so late a—”

“You had to do so due to the demands of your religion. Saturday is your Sabbath day. You were bound by your faith to begin travel only after the sun had well sunk on the horizon.”

“But Holmes,” I interjected. “Why didn’t he come to see us, er, you, during tomorrow’s business?” For Holmes, no observant Anglican himself, was free on Sundays.

“Because, Watson, today was the point of crisis. Our distinguished visitor’s commerce is with the peerage of London. And today, after some four months of slow, steady decline in the price of diamonds, the bottom dropped out of the market, or at least the news reached the pages of the Daily Telegraph. I keep an eye on the prices of commodities, metals, diamonds, and the relative fortunes of national currencies as a matter of my profession.” He shot me a critical glance. “I say, Watson, to those who read your accounts of our adventures in The Strand, I lie about with the newspapers in disarray before me, like a rat in a nest. In reality, I scan intently the several papers which I subscribe to for information about the world. A bit unfair, that.”

I bowed my head slightly, acknowledging the admonishment.