Laurie considered it.
"Well," he said at last, "this may sound very foolish to you; but granting that I have got unusual gifts that way—they are your own words, Mr. Vincent—if that is so, I don't see why my own concentration of thought, or hypnotic sleep or trance or whatever it was—might not have been so intense as to—"
"I quite see," interrupted the other. "That is, of course, conceivable from your point of view. It had occurred to me that you might think that.... Then I take it that your theory is that the subconscious self is sufficient to account for it all—that in this hypnotic sleep, if you care to call it so, you simply uttered what was in your heart, and identified yourself with ... with your memory of that young girl."
"I suppose so," said Laurie shortly.
"And the rapping, loud, continuous, unmistakable?"
"That doesn't seem to me important. I did not actually hear it, you know."
"Then what you need is some unmistakable sign?"
"Yes ... but I see perfectly that this is impossible. Whatever I said in my sleep, either I can't identify it as true, in which case it is worthless as evidence, or I can identify it, because I already know it, and in that case it is worthless again."
The medium smiled, half closing his eyes.
"You must think us very childish, Mr. Baxter," he said.