You have only to talk to him to realize that. Even when I couldn’t follow him I could see that he was not talking nonsense. But the point is that he wants to put it all before you. He is certain that he can make a convert of you.”

“But I don’t know the first thing about science. I have often got up a technical subject for a case, and then washed it out of my mind. I’ve never been instructed in the first principles. I don’t understand the language.”

“That is just why Professor Moe wants you. He says he wants a fresh mind, and a mind trained like yours to weigh evidence. It wasn’t your beaux yeux, Ned, that he fell for, but your reputation as a lawyer.”

“I don’t mind listening to what he has got to say. But look here, Sally, I don’t like this experiment business. What does he propose?”

“Nothing in the least unpleasant. It only means one or two people preparing themselves for an experience, which he says he can give them, by getting into a particular frame of mind. He’s not sure if he can bring it off, you know. The experiment is to be the final proof of his discovery. He was emphatic that there was no danger and no unpleasantness, whether it was successful or not . . . But he was very particular about the people he wanted. He was looking at us all this morning with the queerest appraising eyes. He wants you and Bob especially, and Mr. Mayot and Mr. Tavanger, and possibly Charles. Oh, yes, and he thinks he may want me. But nobody else. He was perfectly clear about that.”

I must say that this rather impressed me. He had chosen exactly those whom I had selected at dinner the previous night as the careful as opposed to the carefree. He wanted people whose physical vitality was low, and who were living on the edge of their nerves, and he had picked them unerringly out of Sally’s house party.

“All right,” I said. “I’ll have a talk to him after dinner. But I want you to be guided by me, and if I think the thing fishy to call it off. If the man is as clever as you say, he may scare somebody into imbecility.”

Before I dressed I rang up Landor, and was lucky enough to find him still in London.