The art of healing was practised among the Chinese in their pre-historic
times, but the earliest efforts of a methodical character, of which
we have any written record, belong to the period with which we are now
dealing. There is indeed a work, entitled "Plain Questions," which is
attributed to a legendary emperor of the Golden Age, who interrogates
one of his ministers on the cause and cure of all kinds of diseases;
as might be expected, it is not of any real value, nor can its date be
carried back beyond a few centuries B.C.

Physicians of the feudal age classified diseases under the four seasons
of the year: headaches and neuralgic affections under _spring_, skin
diseases of all kinds under _summer_, fevers and agues under _autumn_,
and bronchial and pulmonary complaints under _winter_. They treated the
various complaints that fell under these headings by suitable doses of
one or more ingredients taken from the five classes of drugs, derived
from herbs, trees, living creatures, minerals, and grains, each of which
class contained medicines of five flavours, with special properties:
_sour_ for nourishing the bones, _acid_ for nourishing the muscles,
_salt_ for nourishing the blood-vessels, _bitter_ for nourishing general
vitality, and _sweet_ for nourishing the flesh. The pulse has always
been very much to the front in the treatment of disease; there are at
least twenty-four varieties of pulse with which every doctor is supposed
to be familiar, and some eminent doctors have claimed to distinguish
no fewer than seventy-two. In the "Plain Questions" there is a sentence
which points towards the circulation of the blood,--"All the blood is
under the jurisdiction of the heart," a point beyond which the Chinese
never seem to have pushed their investigations; but of this curious
feature in their civilization, later on.