“Exactly. Excessive and a little violent and unnatural. Professor Presbury was rich, however, and there was no objection upon the part of the father. The daughter, however, had other views, and there were already several candidates for her hand, who, if they were less eligible from a worldly point of view, were at least more of an age. The girl seemed to like the professor in spite of his eccentricities. It was only age which stood in the way.

“About this time a little mystery suddenly clouded the normal routine of the professor’s life. He did what he had never done before. He left home and gave no indication where he was going. He was away a fortnight and returned looking rather travel-worn. He made no allusion to where he had been, although he was usually the frankest of men. It chanced, however, that our client here, Mr. Bennett, received a letter from a fellow-student in Prague, who said that he was glad to have seen Professor Presbury there, although he had not been able to talk to him. Only in this way did his own household learn where he had been.

“Now comes the point. From that time onward a curious change came over the professor. He became furtive and sly. Those around him had always the feeling that he was not the man that they had known, but that he was under some shadow which had darkened his higher qualities. His intellect was not affected. His lectures were as brilliant as ever. But always there was something new, something sinister and unexpected. His daughter, who was devoted to him, tried again and again to resume the old relations and to penetrate this mask which her father seemed to have put on. You, sir, as I understand, did the same - but all was in vain. And now, Mr. Bennett, tell in your own words the incident of the letters.”

“You must understand, Dr. Watson, that the professor had no secrets from me. If I were his son or his younger brother I could not have more completely enjoyed his confidence. As his secretary I handled every paper which came to him, and I opened and subdivided his letters. Shortly after his return all this was changed. He told me that certain letters might come to him from London which would be marked by a cross under the stamp. These were to be set aside for his own eyes only. I may say that several of these did pass through my hands, that they had the E. C. mark, and were in an illiterate handwriting. If he answered them at all the answers did not pass through my hands nor into the letter-basket in which our correspondence was collected.”

“And the box,” said Holmes.

“Ah, yes, the box. The professor brought back a little wooden box from his travels. It was the one thing which suggested a Continental tour, for it was one of those quaint carved things which one associates with Germany. This he placed in his instrument cupboard. One day, in looking for a canula, I took up the box. To my surprise he was very angry, and reproved me in words which were quite savage for my curiosity. It was the first time such a thing had happened, and I was deeply hurt. I endeavoured to explain that it was a mere accident that I had touched the box, but all the evening I was conscious that he looked at me harshly and that the incident was rankling in his mind.” Mr. Bennett drew a little diary book from his pocket. “That was on July 2d,” said he.

“You are certainly an admirable witness,” said Holmes. “I may need some of these dates which you have noted.”