is legs, a tap on the great extensor tendon of the
knee-joint just below the patella fails to elicit any quick upward jerk
of the foot, the so-called "knee-kick," then you may be almost sure of
your diagnosis, and proceed to work it out at your leisure.

On the other hand, if an elderly gentleman enters with a curiously blank
and rather melancholy expression of countenance, holding his cane out
stiffly in front of him, and comes toward you at a rapid, toddling gait,
throwing his feet forward in quick, short steps, as if, if he failed to
do so, he would fall on his face, while at the same time a vibrating
tremor carries his head quickly from side to side, you are justified in
suspecting that you have to do with a case of _paralysis agitans_, or
shaking palsy.

Last of all, your physiognomy of disease includes not merely its face,
but its voice; not only the picture that it draws, but the sound that it
makes. For, when all has been allowed and discounted that the most
hardened cynic or pessimistic agnostic can say about speech being given
to man to conceal his thoughts, and the hopeless unreliability of human
testimony, two-thirds of what your patients tell you about their
symptoms will be found to be literally the voice of the disease itself
speaking through them. They may tell you much that is chiefly imaginary,
but even imagination has got to have some physical basis as a
starting-point. They may tell you much that is clearly and ludicrously
irrelevant, or untrue, on account of inaccuracy of observation,
confusion of cause and effect, or a mental color-blindness produced by
the disease itself. But these things can all be brushed aside like the
chaff from the wheat if checked up by the picture of the disease in
plain sight before you.

In the main, the great mass of what patients tell you is of great value
and importance, and, with proper deductions, perfectly reliable. In
fact, I think it would be safe to say that a sharp observer would be
able to make a fairly and approximately accurate diagnosis in seven
cases out of ten, simply by what his eye and his touch tell him while
listening to symptoms recounted by the patient. Time and again have I
seen an examination made of a reasonably intelligent patient, and when
the recital had been finished and the hawk-like gaze had traveled from
head to foot and back again, from ear-tip to finger-nail, from eye to
chest, a symptom which the patient had simply forgotten to mention