“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.