"Such a fantastic theory required strong support," the professor went on. "The clerk helped me. When he came into the house that afternoon and gave his clerk instructions about certain papers Mr. Portman was snappy, his usual self, in fact, and, incidentally, he proved that he had no intention of being away from the office on the following day; when he left the house he was quite different, genially wishing the clerk good night. Wigan, a man slightly overplaying his part would be likely to do that, especially as he wanted the clerk to be in a position to say that his master had gone out at a certain hour. He was bound to draw the clerk's attention to himself, so he did it with a cordial good night. Knowing that Mr. Portman wore glasses, he would also wear them, even in the street." "But the clerk would have seen it was not Mr. Portman," I objected. "That was a difficulty," said Quarles. "It was a foggy afternoon, we know, and would be dark in the passage, but hardly dark enough to deceive the clerk. Another difficulty was how a stranger could get into the house without being seen. Both difficulties vanished when the clerk told us of the man who called selling patent files. He had a bag, Wigan, containing more than samples of files, I warrant--means of disguise as well. We know how easy it is to let the front door slam and remain in the house. I think the file seller practiced the same trick we did. Even to going to Portman's room and hiding behind the screen. You see, the office windows are frosted, so the clerk cannot see whether anyone leaving the office passes into the street or not. If there is something fantastic in this theory, let me pursue it to the end. If I am right, one thing is certain: this file seller knew Portman well. He must have come prepared to make himself up like him. He was able to answer Mrs. Eccles when she knocked at the door and deceive her. Granted that he knew Mr. Portman well, we may assume that he was in some way associated with him in business. Only one man left that room, therefore, as things stand, we may assume that these two men were enemies who had once been friends. Here let me be imaginative for a moment. Mr. Portman was expecting a friend to dine with him on the following night, an important person, since the feast to be prepared was, according to Mrs. Eccles, somewhat elaborate. The sumptuousness of a feast may mean great friendship, but it may be used to hide intense enmity. You read such things in the history of the Medici of Florence. I believe, Wigan, that the feast was prepared for this same file seller, that the wine, which Mr. Portman was looking after himself, remember, would have proved unwholesome for the guest, who, distrusting Portman, came a day earlier and removed his enemy." "A little imaginative," I said.