All these thoughts, as I say, came flocking into my mind together, drawn from various parts of my memory of the morning’s enquiries and observations. They had all presented themselves, in far less time than it takes to read them as set down here, as I was turning over the shoes, confirming my own certainty on the main point. And yet when I confronted the definite idea that had sprung up suddenly and unsupported before me—“_It was not Manderson who was in the house that night_”—it seemed a stark absurdity at the first formulating. It was certainly Manderson who had dined at the house and gone out with Marlowe in the car. People had seen him at close quarters. But was it he who returned at ten? That question too seemed absurd enough. But I could not set it aside. It seemed to me as if a faint light was beginning to creep over the whole expanse of my mind, as it does over land at dawn, and that presently the sun would be rising. I set myself to think over, one by one, the points that had just occurred to me, so as to make out, if possible, why any man masquerading as Manderson should have done these things that Manderson would not have done. I had not to cast about very long for the motive a man might have in forcing his feet into Manderson’s narrow shoes. The examination of footmarks is very well understood by the police. But not only was the man concerned to leave no footmarks of his own: he was concerned to leave Manderson’s, if any; his whole plan, if my guess was right, must have been directed to producing the belief that Manderson was in the place that night. Moreover, his plan did not turn upon leaving footmarks. He meant to leave the shoes themselves, and he did so. The maidservant had found them outside the bedroom door, as Manderson always left his shoes, and had polished them, replacing them on the shoe-shelves later in the morning, after the body had been found. When I came to consider in this new light the leaving of the false teeth, an explanation of what had seemed the maddest part of the affair broke upon me at once. A dental plate is not inseparable from its owner. If my guess was right, the unknown had brought the denture to the house with him, and left it in the bedroom, with the same object as he had in leaving the shoes: to make it impossible that any one should doubt that Manderson had been in the house and had gone to bed there. This, of course, led me to the inference that _Manderson was dead before the false Manderson came to the house_; and other things confirmed this.