“I don’t know. I can only guess. My guess would be that she didn’t see anything.”

“That it was all a mare’s nest?”

“No, no, my dear, I mean that she stood at the pantry window all the afternoon waiting for the young man to come and make it up and that—quite literally—she saw nothing. That is, no one came to the house at all, not the postman, nor anybody else.

“It would take her some time, being slow, to realize that that was very odd—because apparently Mrs. Symmington had received an anonymous letter that afternoon.”

“Didn’t she receive one?” I asked, puzzled.

“But of course not! As I say, this crime is so simple. Her husband just put the cyanide in the top cachet of the ones she took in the afternoon when her sciatica came on after lunch. All Symmington had to do was to get home before, or at the same time as Elsie Holland, call his wife, get no answer, go up to her room, drop a spot of cyanide in the plain glass of water she had used to swallow the cachet, toss the crumpled-up anonymous letter into the grate, and put by her hand the scrap of paper with ‘I can’t go on’ written on it.”

Miss Marple turned to me.

“You were quite right about that, too, Mr. Burton. A ‘scrap of paper’ was all wrong. People don’t leave suicide notes on small torn scraps of paper. They use a sheet of paper—and very often an envelope too. Yes, the scrap of paper was wrong and you knew it.”

“You are rating me too high,” I said. “I knew nothing.”

“But you did, you really did, Mr. Burton. Otherwise why were you immediately impressed by the message your sister left scribbled on the telephone pad?”

I repeated slowly, “‘Say that I can’t go on Friday’—I see! I can’t go on?”

Miss Marple beamed on me.

“Exactly. Mr. Symmington came across such a message and saw its possibilities. He tore off the words he wanted for when the time came—a message genuinely in his wife’s handwriting.”

“Was there any further brilliance on my part?” I asked.

Miss Marple twinkled at me.

“You put me on the track, you know. You assembled those facts together for me—in sequence—and on top of it you told me the most important thing of all—that Elsie Holland had never received any anonymous letters.”

“Do you know,” I said, “last night I thought that she was the letter writer and that that was why there had been no letters written to her?”