"The post-office records show differently. It came to Carlton. I signed for it as an agent of Carlton's. Oh, there's no use going over all that old ground. I've been over it until I thought I was going crazy. I've raked and dug through it, these past three weeks, and nothing's come of it. Nothing can come of it, until Lockwood gets tired of waiting for me to prove what I can't prove!"
"But, out of all the affair as it happened, out of that whole day when the letter came, isn't there one shred or tatter of memory on which you can try to hang something? Isn't there one thing, no matter how small or how misty, from which you can begin?"
"Not one rational thing! I've tried to build a bridge out into that empty space—that day always seems like empty space to me—I've tried to build it out like a cantilever, but I can't bolt two ideas together. I've tried to picture it; I've tried to visualize it; I've tried to imagine it as I must have lived it. But all I've left is the fool idea of a man hitting his thumb."
"What do you mean by that?" I demanded, sitting up with a jolt.
"I keep seeing somebody, somebody sitting in front of me, holding a letter in his right hand and tapping the thumb of his left hand with it as he talked."
"But who is it? Or who was it?"
"I've tried to imagine it was Lockwood."
"Why, you've something right there!" I exultantly cried out. "That's valuable. It's something definite, something concrete, something personal. Let's begin on that."
"It's no use," remarked my companion. His voice, as he spoke, was one of weary unconcern. "I thought the way you do, at first. I felt sure it would lead to something. I kept watching Lockwood, trying to catch him at the trick."
"And?" I prompted.