"What's the other reason?"
"He told me his mother's name. But I am not free to tell it, by reason I promised not to."
This struck the doctor as odd. "How came you to be talking to a stray tramp about his mother, Granny Marrable?" he asked shrewdly.
"Because he took me for his mother, and would have it I should know him." This was no doubt included in what she had promised not to tell, but the question had taken her by surprise.
A light broke on Dr. Nash. All through the interview he had been wondering at himself for never having before observed the likeness between the two old women, which he now saw plainly by the light of the information Gwen had given him. He might have seen it before, had he heard of the gipsy's mistake, but Ruth Thrale had never mentioned this. He remembered, too, in Gwen's story, some slight reference to a son of Mrs. Prichard who was a mauvais sujet. He determined on a daring coup. "Are you sure Mrs. Prichard is not the mother he was looking for?" said he.
Granny Marrable was struck with his cleverness. "Now, how ever did you come to find that out, doctor?" said she.
"We're a clever lot, us doctors! We've got to be clever.... Let's see, now—where are we? Mrs. Prichard has a son who is called by your brother-in-law's name, but who is not your sister's son. Because if he were, Mrs. Prichard would be your sister. Which is impossible. But Mrs. Prichard has got muddled about her own identity, and thinks she is. What can we do to cure such a delusion? I've seen a great deal of this sort of thing—I've had charge of lunatics—and the only thing I know of for the case is to stimulate memory of the patient's actual past life. But we know nothing about Mrs. Prichard. Who the dickens is Mrs. Prichard?"
Granny Marrable had looked really pleased at the reductio ad absurdum—always exhilarating when one knows what's impossible—but looked perplexed over Mrs. Prichard's real identity. "No, indeed, poor dear soul!" she said. "'Tisn't as if there was any would tell us about her."
"I have found, and so has your daughter, that she goes back and back in these dreams of her own childhood, which no doubt are made up of ... which no doubt may have been told her by.... He stopped intentionally. He wanted to stagger her immobility by making her recite the nonsense about Mrs. Prichard's informants.
She was quite amenable. "By little Davy," said she contentedly.