MY subject is Dr. John Thorndyke, the hero or central character of most of my detective stories. So I'll give you a short account of his real origin; of the way in which he did in fact come into existence.

To discover the origin of John Thorndyke I have to reach back into the past for at least fifty years, to the time when I was a medical student preparing for my final examination. For reasons which I need not go into I gave rather special attention to the legal aspects of medicine and the medical aspects of law. And as I read my text-books, and especially the illustrative cases, I was profoundly impressed by their dramatic quality. Medical jurisprudence deals with the human body in its relation to all kinds of legal problems. Thus its subject matter includes all sorts of crime against the person and all sorts of violent death and bodily injury: hanging, drowning, poisons and their effects, problems of suicide and homicide, of personal identity and survivorship, and a host of other problems of the highest dramatic possibilities, though not always quite presentable for the purposes of fiction. And the reported cases which were given in illustration were often crime stories of the most thrilling interest. Cases of disputed identity such as the Tichbourne Case, famous poisoning cases such as the Rugeley Case and that of Madeline Smith, cases of mysterious disappearance or the detection of long-forgotten crimes such as that of Eugene Aram; all these, described and analysed with strict scientific accuracy, formed the matter of Medical Jurisprudence which thrilled me as I read and made an indelible impression.

But it produced no immediate results. I had to pass my examinations and get my diploma, and then look out for the means of earning my living. So all this curious lore was put away for the time being in the pigeon-holes of my mind-which Dr. Freud would call the Unconscious-not forgotten, but ready to come to the surface when the need for it should arise. And there it reposed for some twenty years, until failing health compelled me to abandon medical practice and take to literature as a profession.

It was then that my old studies recurred to my mind. A fellow doctor, Conan Doyle, had made a brilliant and well-deserved success by the creation of the immortal Sherlock Holmes. Considering that achievement, I asked myself whether it might not be possible to devise a detective story of a slightly different kind; one based on the science of Medical Jurisprudence, in which, by the sacrifice of a certain amount of dramatic effect, one could keep entirely within the facts of real life, with nothing fictitious excepting the persons and the events. I came to the conclusion that it was, and began to turn the idea over in my mind.

But I think that the influence which finally determined the character of my detective stories, and incidentally the character of John Thorndyke, operated when I was working at the Westminster Ophthalmic Hospital. There I used to take the patients into the dark room, examine their eyes with the ophthalmoscope, estimate the errors of refraction, and construct an experimental pair of spectacles to correct those errors. When a perfect correction had been arrived at, the formula for it was embodied in a prescription which was sent to the optician who made the permanent spectacles.

Now when I was writing those prescriptions it was borne in on me that in many cases, especially the more complex, the formula for the spectacles, and consequently the spectacles themselves, furnished an infallible record of personal identity. If, for instance, such a pair of spectacles should have been found in a railway carriage, and the maker of those spectacles could be found, there would be practically conclusive evidence that a particular person had travelled by that train. About that time I drafted out a story based on a pair of spectacles, which was published some years later under the title of The Mystery of 31 New Inn, and the construction of that story determined, as I have said, not only the general character of my future work but of the hero around whom the plots were to be woven. But that story remained for some years in cold storage. My first published detective novel was
The Red Thumb-mark, and in that book we may consider that John Thorndyke was born. And in passing on to describe him I may as well explain how and why he came to be the kind of person that he is.

I may begin by saying that he was not modelled after any real person. He was deliberately created to play a certain part, and the idea that was in my mind was that he should be such a person as would be likely and suitable to occupy such a position in real life. As he was to be a medico-legal expert, he had to be a doctor and a fully trained lawyer. On the physical side I endowed him with every kind of natural advantage. He is exceptionally tall, strong, and athletic because those qualities are useful in his vocation. For the same reason he has acute eyesight and hearing and considerable general manual skill, as every doctor ought to have. In appearance he is handsome and of an imposing presence, with a symmetrical face of the classical type and a Grecian nose. And here I may remark that his distinguished appearance is not merely a concession to my personal taste but is also a protest against the monsters of ugliness whom some detective writers have evolved.

These are quite opposed to natural truth. In real life a first-class man of any kind usually tends to be a good-looking man.

Mentally, Thorndyke is quite normal. He has no gifts of intuition or other supernormal mental qualities. He is just a highly intellectual man of great and varied knowledge with exceptionally acute reasoning powers and endowed with that invaluable asset, a scientific imagination (by a scientific imagination I mean that special faculty which marks the born investigator; the capacity to perceive the essential nature of a problem before the detailed evidence comes into sight). But he arrives at his conclusions by ordinary reasoning, which the reader can follow when he has been supplied with the facts; though the intricacy of the train of reasoning may at times call for an exposition at the end of the investigation.

Thorndyke has no eccentricities or oddities which might detract from the dignity of an eminent professional man, unless one excepts an unnatural liking for Trichinopoly cheroots. In manner he is quiet, reserved and self-contained, and rather markedly secretive, but of a kindly nature, though not sentimental, and addicted to occasional touches of dry humour. That is how Thorndyke appears to me.

As to his age. When he made his first bow to the reading public from the doorway of Number 4 King's Bench Walk he was between thirty-five and forty. As that was thirty years ago, he should now be over sixty-five. But he isn't. If I have to let him "grow old along with me" I need not saddle him with the infirmities of age, and I can (in his case) put the brake on the passing years. Probably he is not more than fifty after all!

Now a few words as to how Thorndyke goes to work. His methods are rather different from those of the detectives of the Sherlock Holmes school. They are more technical and more specialized. He is an investigator of crime but he is not a detective. The technique of Scotland Yard would be neither suitable nor possible to him. He is a medico-legal expert, and his methods are those of medico-legal science. In the investigation of a crime there are two entirely different methods of approach. One consists in the careful and laborious examination of a vast mass of small and commonplace detail: inquiring into the movements of suspected and other persons; interrogating witnesses and checking their statements particularly as to times and places; tracing missing persons, and so forth-the aim being to accumulate a great body of circumstantial evidence which will ultimately disclose the solution of the problem. It is an admirable method, as the success of our police proves, and it is used with brilliant effect by at least one of our contemporary detective writers. But it is essentially a police method.

The other method consists in the search for some fact of high evidential value which can be demonstrated by physical methods and which constitutes conclusive proof of some important point. This method also is used by the police in suitable cases. Finger-prints are examples of this kind of evidence, and another instance is furnished by the Gutteridge murder. Here the microscopical examination of a cartridge-case proved conclusively that the murder had been committed with a particular revolver; a fact which incriminated the owner of that revolver and led to his conviction.

This is Thorndyke's procedure. It consists in the interrogation of things rather than persons; of the ascertainment of physical facts which can be made visible to eyes other than his own. And the facts which he seeks tend to be those which are apparent only to the trained eye of the medical practitioner.

I feel that I ought to say a few words about Thorndyke's two satellites, Jervis and Polton. As to the former, he is just the traditional narrator proper to this type of story. Some of my readers have complained that Dr. Jervis is rather slow in the uptake. But that is precisely his function. He is the expert misunderstander. His job is to observe and record all the facts, and to fail completely to perceive their significance. Thereby he gives the reader all the necessary information, and he affords Thorndyke the opportunity to expound its bearing on the case.

Polton is in a slightly different category. Although he is not drawn from any real person, he is associated in my mind with two actual individuals. One is a Mr. Pollard, who was the laboratory assistant in the hospital museum when I was a student, and who gave me many a valuable tip in matters of technique, and who, I hope, is still to the good. The other was a watch- and clock-maker of the name of Parsons -familiarly known as Uncle Parsons-who had premises in a basement near the Royal Exchange, and who was a man of boundless ingenuity and technical resource. Both of these I regard as collateral relatives, so to speak, of Nathaniel Polton. But his personality is not like either. His crinkly countenance is strictly his own copyright.

To return to Thorndyke, his rather technical methods have, for the purposes of fiction, advantages and disadvantages. The advantage is that his facts are demonstrably true, and often they are intrinsically interesting. The disadvantage is that they are frequently not matters of common knowledge, so that the reader may fail to recognize them or grasp their significance until they are explained. But this is the case with all classes of fiction. There is no type of character or story that can be made sympathetic and acceptable to every kind of reader. The personal equation affects the reading as well as the writing of a story.