“I have no doubt, sir, that you are fully competent, but I am sure that you will agree that in such a case a second opinion is valuable. You have avoided this, I understand, for fear that pressure should be put upon you to segregate the patient.”

“That is so,” said Colonel Emsworth.

“I foresaw this situation,” I explained, “and I have brought with me a friend whose discretion may absolutely be trusted. I was able once to do him a professional service, and he is ready to advise as a friend rather than as a specialist. His name is Sir James Saunders.”

The prospect of an interview with Lord Roberts would not have excited greater wonder and pleasure in a raw subaltern than was now reflected upon the face of Mr. Kent.

“I shall indeed be proud,” he murmured.

“Then I will ask Sir James to step this way. He is at present in the carriage outside the door. Meanwhile, Colonel Emsworth, we may perhaps assemble in your study, where I could give the necessary explanations.”

And here it is that I miss my Watson. By cunning questions and ejaculations of wonder he could elevate my simple art, which is but systematized common sense, into a prodigy. When I tell my own story I have no such aid. And yet I will give my process of thought even as I gave it to my small audience, which included Godfrey’s mother in the study of Colonel Emsworth.

“That process,” said I, “starts upon the supposition that when you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth. It may well be that several explanations remain, in which case one tries test after test until one or other of them has a convincing amount of support. We will now apply this principle to the case in point. As it was first presented to me, there were three possible explanations of the seclusion or incarceration of this gentleman in an outhouse of his father’s mansion. There was the explanation that he was in hiding for a crime, or that he was mad and that they wished to avoid an asylum, or that he had some disease which caused his segregation. I could think of no other adequate solutions. These, then, had to be sifted and balanced against each other.

“The criminal solution would not bear inspection. No unsolved crime had been reported from that district. I was sure of that. If it were some crime not yet discovered, then clearly it would be to the interest of the family to get rid of the delinquent and send him abroad rather than keep him concealed at home. I could see no explanation for such a line of conduct.

“Insanity was more plausible. The presence of the second person in the outhouse suggested a keeper. The fact that he locked the door when he came out strengthened the supposition and gave the idea of constraint. On the other hand, this constraint could not be severe or the young man could not have got loose and come down to have a look at his friend. You will remember, Mr. Dodd, that I felt round for points, asking you, for example, about the paper which Mr. Kent was reading. Had it been the Lancet or the British Medical Journal it would have helped me. It is not illegal, however, to keep a lunatic upon private premises so long as there is a qualified person in attendance and that the authorities have been duly notified. Why, then, all this desperate desire for secrecy? Once again I could not get the theory to fit the facts.