"The secret is," he said; and then stopped as if unable to go on. Then he began again and said:
"You see, it was I who killed all those people."
"What?" repeated the other, in a small voice out of a vast silence.
"You see, I had murdered them all myself," explained Father Brown patiently. "So, of course, I knew how it was done."
Grandison Chace had risen to his great height like a man lifted to the ceiling by a sort of slow explosion. Staring down at the other he repeated his incredulous question.
"I had planned out each of the crimes very carefully," went on Father Brown, "I had thought out exactly how a thing like that could be done, and in what style or state of mind a man could really do it. And when I was quite sure that I felt exactly like the murderer myself, of course I knew who he was."
Chace gradually released a sort of broken sigh.
"You frightened me all right," he said. "For the minute I really did think you meant you were the murderer. Just for the minute I kind of saw it splashed over all the papers in the States: 'Saintly Sleuth Exposed as Killer: Hundred Crimes of Father Brown.' Why, of course, if it's just a figure of speech and means you tried to reconstruct the psychology——"
Father Brown rapped sharply on the stove with the short pipe he was about to fill; one or his very rare spasms of annoyance contracted his face.
"No, no, no," he said, almost angrily; "I don't mean just a figure of speech. This is what comes of trying to talk about deep things.... What's the good of words?... If you try to talk about a truth that's merely moral, people always think it's merely metaphorical. A real live man with two legs once said to me: 'I only believe in the Holy Ghost in a spiritual sense.' Naturally, I said: 'In what other sense could you believe it?' And then he thought I meant he needn't believe in anything except evolution, or ethical fellowship, or some bilge.... I mean that I really did see myself, and my real self, committing the murders. I didn't actually kill the men by material means; but that's not the point. Any brick or bit of machinery might have killed them by material means. I mean that I thought and thought about how a man might come to be like that, until I realized that I really was like that, in everything except actual final consent to the action. It was once suggested to me by a friend of mine, as a sort of religious exercise. I believe he got it from Pope Leo XIII, who was always rather a hero of mine."