Just as rabbit-burrows on the Arizona plain give shelter to a mixed tenantry, a rabbit, an owl, and a snake often occupying the same hole, so the Harley Street houses are, as a rule, divided up between dentists, oculists, surgeons, and physicians, so that under the same roof you can, if you are so minded, have your teeth extracted, your lungs percussed, your eyes put right, and your surgical ailment seen to, each on a different floor. Number 110A, Harley Street, however, contained only one occupant—Dr. Otto Oppenshaw. Dr. Oppenshaw had no need of a sharer in his rent burdens; a neurologist in the most nerve-ridden city of Europe, he was making an income of some twenty-five thousand a year.

People were turned away from his door as from a theatre where a wildly successful play is running. The main craving of fashionable neurotics, a craving beyond, though often inspired by the craving for, the opium alkaloids and cocaine, was to see Oppenshaw. Yet he was not much to see: a little bald man like a turnip, with the manners of a butcher, and gold-rimmed spectacles.

Dukes inspired with the desire to see Oppenshaw had to wait their turn often behind tradesmen, yet he was at Simon Pettigrew's command. Simon was his sometime lawyer. It was half-past twelve, or maybe a bit more, when the taxi drew up at 110A and the lawyer, after a sharp legal discussion over tuppence with the driver, mounted the steps and pressed the bell.

The door was at once opened by a pale-faced man in black, who conducted the visitor to the waiting-room, where a single patient was seated reading a last year's volume of Punch and not seeming to realise the jokes.

This person was called out presently, and then came Simon's turn.

Oppenshaw got up from his desk and came forward to meet him.

"I'm sorry to bother you," said Simon, when they had exchanged greetings. "It's a difficult matter I have come to consult you about, and an important one, else I would not have cut into your time like this."

"State your case," said the other jovially, retaking his seat and pointing out a chair.

"That's the devil of it," replied Simon; "it's a case that lies out of the jurisdiction of common sense and common knowledge. Look at me. Do I look as though I were a dreamer or creature of fancies?"

"You certainly don't," said Oppenshaw frankly.

"Yet what I have to tell you disgusts me—will disgust you."

"I'm used to that, I'm used to that," said the other. "Nothing you can say will alarm, disgust, or leave me incredulous."

"Well, here it is," said the patient, plunging into the matter as a man into cold water. "A year ago—a year and four weeks, for it was on the third of May—I went down to my office one morning and transacted my business as usual. At twelve o'clock I—er—had occasion to open my safe, a safe of which I alone possess the key. On the top of a deed-box in that safe I found a brown-paper parcel tied with red tape. I was astonished, for I had put no parcel in."

"You might have forgotten," said Oppenshaw.

"I never forget," replied Simon.

"Go on," said Oppenshaw.

"I opened the parcel. It contained bank-notes to the amount of ten thousand pounds."

"H'm—h'm."

"Ten thousand pounds. I could not believe my eyes. I sent for my chief clerk, Brownlow. He could not believe his eyes, and I fear he even doubted the statement of the whole case. Now listen. I determined to go to my bank, Cumber's, and make enquiries as to my balance, ridden by the seemingly absurd idea that I myself had drawn this amount and forgotten the fact. I may say at once this was the truth, I had drawn it, unknown to myself. Well, that was the third of May, and when and where do you think I found myself next?"

"Go on," said Oppenshaw.

"In Paris on the third of June."

"Ah—ah."

"Everything between those dates was a blank."

"Your case is not absolutely common," said Oppenshaw. "Rare, but not without precedent—read the papers. Why, only yesterday a woman was found on a seat at Brighton. She had left London a week ago; the interval was to her a complete blank, yet she had travelled about and lived like an ordinary mortal in possession of her ordinary senses."

"Wait a bit," said Simon. "I was not found on a seat in Paris. I found myself in a gorgeously-furnished sitting-room of the Bristol Hotel, and I was dressed in clothes that might have suited a young man—a fool of twenty, and I very soon found that I had been acting—acting like a fool. Of the ten thousand only five thousand remained."

"Five thousand in a month," said Oppenshaw. "Well, you paid the price of your temporary youth. Tell me," said he, "and be quite frank. What were you like when you were young? I mean in mind and conduct?"

Simon moved wearily.

"I was a fool for a while," said he. "Then I suddenly checked myself and became sensible."

Oppenshaw rapped twice with his fingers on his desk as if in triumph over his own perception.

"That clears matters," said he. "You were undoubtedly suffering from Lethmann's disease."

"Good Lord!" said Simon. "What's that?"

"It's a form of aberration—most interesting. You have heard of double personalities, of which a great deal of nonsense has been written? Well, Lethmann's disease is just this: a man, say, of twenty, suddenly checked in the course of his youth, becomes practically another person. You, for instance, became, or fancied you became, another person; you suddenly 'checked yourself and became sensible,' as you put it, but you did not destroy that old foolish self. Nothing is destructible in mind as long as the brain-tissue is normal; you put it in prison, and after the lapse of many years, owing, perhaps, to some slight declension in brain power, it broke out, dominated you, and lived again. Youth must be served.

"It would have been perhaps better for you to have let your youth run its course and expend itself normally. You have paid the price of your own will-power. I am very much interested in this. Tell me as faithfully as you can what you did in Paris, or at least what you gathered that you did. When you came to, did you remember your actions during the month of aberration?"

"When I came to," said Simon, speaking almost with his teeth set, "I was like a person stunned. Then I remembered, bit by bit, what I had been doing, but it was like vaguely remembering what another man had been doing."

"Right," said Oppenshaw, "that tallies with your case. Go on."

"I had been doing foolish things. I had been living, so to say, on the surface of life, without a thought of anything but pleasure, without the slightest recollection of myself as I am. I had been doing things that I might have done at twenty—extravagant follies; yet I believe not any really vicious acts. I had been drinking too much champagne, for one thing, and there were several ladies.... Good Lord! Oppenshaw, I'd blush to confess it to anyone else, but I'd been going on like a boy, picking flowers at Fontainebleau—writing verses to one of these hussies. I could remember that. Me!—verses about blue skies and streams and things! Me! It's horrible!"

"Used you to write verses when you were young?"

"Yes," said Simon, "I believe I used to make that sort of fool of myself."

"You were full of the joy of living?"

"I suppose so."

"You see, everything tallies. Yes, without any manner of doubt it's a case of Lethmann's disease rounded and complete. Now, tell me, when you came to, you could remember all your actions in Paris; how far back did that memory go?"

"I could remember dimly right back to when I was leaving the office in Old Serjeants' Inn with the bundle of bank-notes to go to the bank. Then all of a sudden it would seem I forgot all about my past and became, as you insist, myself at twenty. I went to the Charing Cross Hotel, where I had already, it would seem, hired rooms for myself, and where I had directed new clothes to be sent, and then I went to Paris."

"This is most important," said Oppenshaw. "You had already hired rooms for yourself and ordered clothes. Those acts must have been committed before the great change came on you, and of course without your knowledge."

"They must. Also the act of drawing the ten thousand from the bank."

"The concealed other self must have been working like a mole in the dark for some days at least," said Oppenshaw, "utterly without your knowledge."

"Utterly."

"Then having prepared in a vague sort of way a means for enjoying itself, it burst out; it was like a butterfly coming out of a chrysalis—excuse the simile."

"Something like that."

"So far so good. Well, now, when you came to your old self in Paris, what did you do?"

"I came back to London, of course."

"But surely your sudden disappearance must have caused alarm? Why, it would have been in the papers."

"Not a bit," said Simon grimly. "My other self, as you call it, had prepared for that. It seems the night before the thing happened I told Mudd—you know Mudd, the butler—that I might be called away suddenly and be absent a considerable time, that I would buy clothes and nightshirts and things, if that was so, at the place I was going to, and that he was to tell the office if I went away, and to tell Brownlow to carry on. Infernal, isn't it?"

"Infernally ingenious," said Oppenshaw; "but if you had ever studied the subject of duplex personality you would not be surprised. I have seen a young religious girl make most complex preparations for a journey as a missionary to China, utterly without her own knowledge. We caught her at the station, fortunately, just in time—but how did you find out that you gave Mudd those instructions?"

"The whole way back from Paris," said Simon, "I was preparing to meet all sorts of enquiry and bother as to my absence. Then, when I reached home, Mudd did not seem to think it out of the way; he told me he had followed my directions and notified the office when I did not return, and told them that I might be some time away. Then I got out of him what I had said about the clothes and so on."

"Tell me," said Oppenshaw suddenly, "why did you come to me to-day to tell me all this?"

"Because," said Simon, "on opening my safe this morning I found in a wallet on the top of the deed-box another bundle of notes for exactly the same amount."