Holmes was pacing up and down one side of the room whilst the old professor was talking. I observed that he was smoking with extraordinary rapidity. It was evident that he shared our host’s liking for the fresh Alexandrian cigarettes.

“Yes, sir, it is a crushing blow,” said the old man. “That is my magnum opus - the pile of papers on the side table yonder. It is my analysis of the documents found in the Coptic monasteries of Syria and Egypt, a work which will cut deep at the very foundation of revealed religion. With my enfeebled health I do not know whether I shall ever be able to complete it, now that my assistant has been taken from me. Dear me! Mr. Holmes, why, you are even a quicker smoker than I am myself.”

Holmes smiled.

“I am a connoisseur,” said he, taking another cigarette from the box - his fourth - and lighting it from the stub of that which he had finished. “I will not trouble you with any lengthy cross-examination, Professor Coram, since I gather that you were in bed at the time of the crime, and could know nothing about it. I would only ask this: What do you imagine that this poor fellow meant by his last words: ‘The professor - it was she’?”

The professor shook his head.

“Susan is a country girl,” said he, “and you know the incredible stupidity of that class. I fancy that the poor fellow murmured some incoherent, delirious words, and that she twisted them into this meaningless message.”

“I see. You have no explanation yourself of the tragedy?”

“Possibly an accident, possibly - I only breathe it among ourselves - a suicide. Young men have their hidden troubles - some affair of the heart, perhaps, which we have never known. It is a more probable supposition than murder.”

“But the eyeglasses?”

“Ah! I am only a student - a man of dreams. I cannot explain the practical things of life. But still, we are aware, my friend, that love-gages may take strange shapes. By all means take another cigarette. It is a pleasure to see anyone appreciate them so. A fan, a glove, glasses - who knows what article may be carried as a token or treasured when a man puts an end to his life? This gentleman speaks of footsteps in the grass, but, after all, it is easy to be mistaken on such a point. As to the knife, it might well be thrown far from the unfortunate man as he fell. It is possible that I speak as a child, but to me it seems that Willoughby Smith has met his fate by his own hand.”

Holmes seemed struck by the theory thus put forward, and he continued to walk up and down for some time, lost in thought and consuming cigarette after cigarette.

“Tell me, Professor Coram,” he said, at last, “what is in that cupboard in the bureau?”

“Nothing that would help a thief. Family papers, letters from my poor wife, diplomas of universities which have done me honour. Here is the key. You can look for yourself.”

Holmes picked up the key, and looked at it for an instant, then he handed it back.

“No, I hardly think that it would help me,” said he. “I should prefer to go quietly down to your garden, and turn the whole matter over in my head. There is something to be said for the theory of suicide which you have put forward. We must apologize for having intruded upon you, Professor Coram, and I promise that we won’t disturb you until after lunch. At two o’clock we will come again, and report to you anything which may have happened in the interval.”

Holmes was curiously distrait, and we walked up and down the garden path for some time in silence.

“Have you a clue?” I asked, at last.

“It depends upon those cigarettes that I smoked,” said he. “It is possible that I am utterly mistaken. The cigarettes will show me.”