than younger ones." [Dr. James Jackson
has kindly permitted me to make the following extract from a letter
just received by him from Sir James Clark, and dated May 26, 1860: "As a
physician advances in age, he generally, I think, places less confidence
in the ordinary medical treatment than he did, not only during his
early, but even his middle period of life."] The conclusion from these
facts is one which the least promising of Dr. Howe's pupils in the
mental department could hardly help drawing.

Part of the blame of over-medication must, I fear, rest with the
profession, for yielding to the tendency to self-delusion, which seems
inseparable from the practice of the art of healing. I need only touch
on the common modes of misunderstanding or misapplying the evidence of
nature.

First, there is the natural incapacity for sound observation, which is
like a faulty ear in music. We see this in many persons who know a good
deal about books, but who are not sharp-sighted enough to buy a horse or
deal with human diseases.

Secondly, there is in some persons a singular inability to weigh the
value of testimony; of which, I think, from a pretty careful examination
of his books, Hahnemann affords the best specimen outside the walls of
Bedlam.

The inveterate logical errors to which physicians have always been
subject are chiefly these:

The mode of inference per enumerationem simplicem, in scholastic phrase;
that is, counting only their favorable cases. This is the old trick
illustrated in Lord Bacon's story of the gifts of the shipwrecked
people, hung up in the temple.--Behold! they vowed these gifts to the
altar, and the gods saved them. Ay, said a doubting bystander, but
how many made vows of gifts and were shipwrecked notwithstanding? The
numerical system is the best corrective of this and similar errors. The
arguments commonly brought against its application to all matters of
medical observation, treatment included, seem to apply rather to the
tabulation of facts ill observed, or improperly classified, than to the
method itself.

The post hoc ergo propter hoc error: he got well after taking my
medicine; therefore in consequence of taking it.

The false induction from genuine facts of observation, leading to the
construction of theories which are then deductively applied in the
face of the results of direct observation. The school of Broussais has
furnished us with a good example of this error.

And lastly, the