Musing thus, he turned to walk down the great central staircase of the hospital. As he did so, his attention was attracted for a moment by a singular person who was descending the opposite stair towards the same landing. This person was tall and not ill-looking; but, as he came down the steps, he kept pursing up his mouth and cheeks into the most extraordinary and hideous grimaces; in fact, he was obviously making insulting faces at Arthur Greatrex. Arthur was so much preoccupied at the moment, however, that he hardly had time to notice the eccentric stranger; and, as he took him for one of the harmless lunatic patients in the mental-diseases ward, he would have passed on without further observing the man but for an odd circumstance which occurred as they both reached the great central landing together. Arthur happened to drop the book he was carrying from under his arm, and instinctively stooped to pick it up. At the same moment the grimacing stranger dropped his own book also, not in imitation, but by obvious coincidence, and stooped to pick it up with the self-same gesture. Struck by the oddity of the situation, Arthur turned to look at the curious patient. To his utter horror and surprise, he discovered that the man he had been observing was his own reflection. In one second the real state of the case flashed like lightning across his bewildered brain. There was no opposite staircase, as he knew very well, for he had been down those steps a hundred times before: nothing but a big mirror, which reflected and doubled the one-sided flight from top to bottom. It was only his momentary preoccupation which had made him for a minute fall into the obvious delusion. The man whom he saw descending towards him was really himself, Arthur Greatrex. Even so, he did not at once grasp the full strangeness of the scene he had just witnessed. It was only as he turned to descend again that he caught another glimpse of himself in the big mirror, and saw that he was still making the most horrible and ghastliest grimaces--grimaces such as he had never seen equalled save by the monkeys at the Zoo, and (horridest thought of all!) by the worst patients in the mental-disease ward. He pulled himself up in speechless horror, and looked once more into the big mirror. Yes, there was positively no mistaking the fact: it was he, Arthur Greatrex, fellow of Catherine's, who was making these hideous and meaningless distortions of his own countenance.