PROLOGUE

_Martin Hesselius, the German Physician_

Though carefully educated in medicine and surgery, I have never
practised either. The study of each continues, nevertheless, to interest
me profoundly. Neither idleness nor caprice caused my secession from the
honourable calling which I had just entered. The cause was a very
trifling scratch inflicted by a dissecting knife. This trifle cost me
the loss of two fingers, amputated promptly, and the more painful loss
of my health, for I have never been quite well since, and have seldom
been twelve months together in the same place.

In my wanderings I became acquainted with Dr. Martin Hesselius, a
wanderer like myself, like me a physician, and like me an enthusiast in
his profession. Unlike me in this, that his wanderings were voluntary,
and he a man, if not of fortune, as we estimate fortune in England, at
least in what our forefathers used to term "easy circumstances." He was
an old man when I first saw him; nearly five-and-thirty years my senior.

In Dr. Martin Hesselius, I found my master. His knowledge was immense,
his grasp of a case was an intuition. He was the very man to inspire a
young enthusiast, like me, awe and delight. My admiration has stood
the test of time and survived the separation of death. I am sure it was
well-founded.

For nearly twenty years I acted as his medical secretary. His immense
collection of papers he has left in my care, to be arranged, indexed and
bound. His treatment of some of these cases is curious. He writes in two
distinct characters. He describes what he saw and heard as an
intelligent layman might, and when in this style of narrative he had
seen the patient either through his own hall-door, to the light of day,
or through the gates of darkness to the caverns of the dead, he returns
upon the narrative, and in the terms of his art and with all the force
and originality of genius, proceeds to the work of analysis, diagnosis
and illustration.

Here and there a case strikes me as of a kind to amuse or horrify a lay
reader an interest quite different from the peculiar one which it
may possess for an expert. With slight modifications, chiefly of
language, and of course a change of names, I copy the following. The
narrator is Dr. Martin Hesselius. I find it among the voluminous notes
of cases which he made during a tour in England about sixty-four years
ago.

It is related in series of letters to his friend Professor Van Loo of
Leyden. The professor was not a physician, but a chemist, and a man who
read history and metaphysics and medicine, and had, in his day, written
a play.

The narrative is therefore, if somewhat less valuable as a medical
record, necessarily written in a manner more likely to interest an
unlearned reader.

These letters, from a memorandum attached, appear to have been returned
on the death of the professor, in 1819, to Dr. Hesselius. They are
written, some in English, some in French, but the greater part in
German. I am a faithful,