Thus it was that at four-eighteen, the three of us were in a first-class smoking compartment as our train puffed its way noisily beneath blackened girders up the steep incline from Liverpool Street towards the higher ground of Essex.

“Mr Harte’s satchel and its contents are singularly suggestive, are they not?” said Holmes to me. “They help one to form a clear picture of the man to whom the satchel belongs. I take it you drew the same inferences from these materials as I did.”

“There are certainly some indications,” I returned cautiously. “It is evident, for instance, that the owner of the satchel is an enthusiast for English literature.”

“But not one of very long standing.”

“Why so?”

“The book describing the history of English literature, worthy volume though it is, is introductory in nature and written for a general audience. The fact that it is clearly new, and evidently recently purchased, suggests that its owner, however enthusiastic he might be, is not yet in an advanced stage of literary scholarship.”

“That may be so,” I returned, “but the book is inscribed, and thus may be a present from a friend. In which case, of course, you cannot so reliably judge the owner’s level of sophistication and scholarship from it.”

“Generally speaking,” said Holmes, “that would be a sound observation. Your attention to detail does you credit.”

“Thank you.”

“In this particular case, however, your reasoning is erroneous.”

“Why?”

“There are two distinct parts to the inscription. The first part, at the top, consists of the initials ‘A. K.’, the second part is the remainder, ‘Kindest regards. Your friend, D. W.’, if I recall it aright.”

“These two parts, as you call them, seemed all one to me.”

“Not at all. Not only are the initials ‘A. K.’ in a different hand, they are written with a different pen.”

“Let us see,” said Harte, unfastening the satchel and taking out the book.

“You may be correct,” I conceded as I examined the inscription.

“I am certain of it,” said Holmes. “The ‘K’ in ‘A. K.’ is formed quite differently from the ‘K’ in ‘Kindest regards’. Now, this suggests that the owner of the book, whom we must presume is this ‘A. K.’ – for the book is undoubtedly a new one and has not been owned by anyone before – bought the book himself and wrote his initials in it, and only subsequently asked his friend to inscribe it. You will note that the inscription says neither ‘To A. K.’ nor ‘From D. W.’ but simply ‘Kindest regards, your friend, D. W.’”

“But why should he ask his friend to write in his book if his friend did not buy the book for him?” asked Harte in a tone of puzzlement.

“The friend may not have bought the book,” returned Holmes, “but it appears likely that he has played a significant part in the business.”

“What do you mean?”

“Simply that the friend – ‘D. W.’ – is almost certainly the author of the book.”

I glanced at the book’s title page. “Of course, you must be right!” I cried as I read the name of Professor David Walters of Trinity College, Cambridge.

“It seems likely, then, that ‘A. K.’ – the man you met on the train, Mr Harte – had bought himself this book while in Cambridge to attend a lecture. There is a little gummed label on the inside of the back cover, giving the name of the bookshop. No doubt the brown paper and string in the satchel came from that shop, too. We do not know whether the lecture that ‘A. K.’ attended was given by Professor Walters, but whether it was or not, ‘A. K.’ must have approached Professor Walters at some time during the day and asked him to inscribe this book for him. If the two men were strangers, Professor Walters would surely have satisfied the request by writing ‘Best wishes’, or something of the sort. But he has specifically called himself ‘Your friend, D. W.’, so we must suppose that the two men are well acquainted. Professor Walters is an eminent figure in the world of scholars, and it is a fair assumption that many of his acquaintances are from that same class of society, including, perhaps, the man calling himself Dr Kennett. We are, you see, slowly but surely building up a picture of that gentleman.”

“It is not conclusive,” I observed.

“No, it is not, I agree, but the balance of probability surely lies upon that side. Dr Kennett is certainly highly intelligent and highly educated, as Mr Harte’s testimony of their lengthy literary discussion attests. In any investigation, it is of course preferable if one can deduce one fact from another, and then a third from the second, and so on. Sometimes, however, the data are so meagre that it is not possible to make such deductions with any certainty. In that case, one must construct a tentative hypothesis, and be prepared to alter it at any time, if new facts come to light. The process is somewhat akin to the erection of his wigwam by a Red Indian. None of the poles he uses, taken alone, can possibly support the wigwam, but when he has several poles leaning together, each providing mutual support for the others, the structure can stand. Thus it is in this case: none of the deductions we can make from the satchel or its contents are certain. Taken all together, however, they lend fairly sturdy support to the wigwam of our hypothesis, and we can thus feel a reasonable degree of confidence in our conclusions. If we turn now to the other volume in the satchel, Dickens’s David Copperfield: this appears to have been read before, but not more than once, I should say. It is not by any means what might be described as ‘a well-thumbed copy’, and in fact appears to be a fairly recent edition.”

“That is true,” I agreed.

“Now, while it is possible that Dr Kennett had already read David Copperfield in a different edition when he was younger, it seems most likely, taking the condition of this volume together with his remarks about the book, that it is a novel he has come to for the first time only recently, in maturity.”

“That had not struck me before,” said Harte in a considered tone, “but now that I recall again his conversation, I am inclined to think that what you suggest is correct.”

“But as Kennett himself observed, David Copperfield is commonly given to children of fourteen and fifteen years of age. How is it, then, that such an intelligent and cultured man as Kennett should never have read the book before?”

“Perhaps because all his intellectual energies have been applied to other subjects,” I suggested.

“It is possible,” said Holmes. “Perhaps, like John Stuart Mill, he had an education which was rigorously devoted to scientific and technical subjects, to the exclusion of the more artistic aspects of human life. Mill writes somewhere that because of the intense educational process to which he was subjected, which had been devised by his father, he heard scarcely a note of music or a word of poetry until he was an adult. But in this case, other, simpler, explanations are possible.”

“What do you have in mind?” asked Harte.

“That the man calling himself Dr Kennett is not in fact English. If that were so, he might, of course, be highly educated, and perhaps familiar with the literature of his own country, but not with that of England.”

“He certainly sounded English,” observed Harte. “He had no particular accent that I could discern.”

“Well it is, of course, possible that although foreign, he has been a fluent English-speaker for many years. Some foreign English-speakers – those from France and the other Latin countries, for instance – never really lose their original accents, no matter how long they live in England, but for others – some Germans and Scandinavians, for instance – the speaking of English seems to come more naturally, and after living here for a few years many of them could pass for natives. Perhaps it is so with Kennett. The conjecture that he is a foreigner is, of course, but one of half a dozen different possible explanations, but I will not trouble you with the others, all of which I was able to eliminate in light of the data presented to us by the satchel. May I now draw your attention to the inscription on the inside of the satchel?”