To us, no doubt, it is surprising that so many brilliant people took spiritualism seriously. Sir William Crookes, the inventor of the cathode tube, and winner of the Nobel prize for physics, was a firm believer. Charles Richet, who won the Nobel prize for medicine in 1913 for his elucidation of anaphylaxis, spent most of the last part of his life writing books with titles such as The Great Hope.

But the most famous medical believer in spiritualism was Sir Arthur Conan Doyle. He had hoped that he would be remembered more for his spiritualist work than for Sherlock Holmes, but it was not to be. In 1918, he wrote a short book called The New Revelation, a prelude to his two volume history of spiritualism. Sir Arthur relates the kind of evidence that impressed him:

A lady in whom I was interested had died in a provincial town. She was a chronic invalid, and morphia was found by her bedside. There was an inquest with an open verdict. Eight days later I went to have a sitting with Mr Vout Peters [a favourite medium, incidentally, of Sir Oliver Lodge]. After giving a good deal which was vague and irrelevant, he suddenly said, “There is a lady here. She is leaning upon an older woman. She keeps saying ‘Morphia.’ Three times she has said it. Her mind was clouded. She did not mean it. Morphia!” Those were almost his exact words.

Sir Arthur, being a very nice man, could not bring himself to believe in Hell, but he did believe in what he called “probationary spheres,” for those who had not done well (morally) in life. These, he said, “should perhaps rather be looked upon as a hospital for weakly souls than as a penal community”: a kind of celestial unit for personality disorders, I suppose.