The doctrine of the “humours,” or humoral pathology, as it is generally
termed, is usually traced to Hippocrates. It is set forth in his book
on the Nature of Man, which Galen regarded as a genuine treatise of the
Physician of Cos, but which other critics have supposed to have been
written by one or more of his disciples or successors. At any rate, it
is believed to represent his views. Plato elaborated the theory, and
Galen gave it dogmatic form.
The human body was composed not exactly of the four elements, earth,
air, fire, and water, but of the essences of these elements. The fluid
parts, the blood, the phlegm, the bile, and the black bile, were the
four humours. There were also three kinds of spirits, natural, vital,
and animal, which put the humours in motion.
The blood was the humour which nourished the various parts of the
body, and was the source of animal heat. The bile kept the passages of
the body open, and served to promote the digestion of the food. The
phlegm kept the nerves, the muscles, the cartilages, the tongue, and
other organs supple, thus facilitating their movements. The black bile
(the melancholy, Hippocrates termed it) was a link between the other
humours and sustained them. The proportion of these humours occasioned
the temperaments, and it is hardly necessary to remark that this
fancy still prevails in our language; the sanguine, the bilious, the
phlegmatic, and the atrabilious or melancholy natures being familiar
descriptions to this day.
The humours had different characters. The blood was naturally hot and
humid, the phlegm cold and humid, the bile hot and dry, and the black
bile cold and dry. Alterations of the humours would cause diseased
conditions; distempers was the appropriate term. There might be a too
abundant provision of one or more of the humours. A plethora of blood
would cause drowsiness, difficulty of breathing, fatty degeneration.
A plethora of either of the other humours would have the effect of
causing corruption of the blood; plethora of bile, for example,
would result in a jaundiced condition, bad breath, a bitter taste in
the mouth, and other familiar symptoms. Hæmorrhoids, leprosy, and
cancer might result from a plethora of the melancholic humour; colds,
catarrhs, rheumatisms were occasioned by a superabundance of the phlegm.
It must not be supposed that Galen or any other authority pretended
that the humours were the sole causes of disease. Ancient pathology
was a most complicated structure which cannot be even outlined here.
The theory of the humours is only indicated in order to show how these
explained the action of drugs. To these were attributed hot, humid,
cold, and dry qualities to a larger or less extent. Galen classifies
them in four degrees--that is to say, a drug might be hot, humid, cold,
or dry in the first, second, third, or fourth degree. Consequently the
physician had to estimate first which humour was predominant, and in
what degree, and then he had to select the drug which would counteract
the disproportionate heat, cold, humidity, or dryness. Of course he
had his manuals to guide him. Thus Culpepper tells us that horehound,
for example, is “hot in the second degree, and dry in the third”; herb
Trinity, or pansies, on the other hand, “are cold and moist, both herbs
and flowers”; and so forth. Medicines which applied to the skin would
raise a blister, mustard, for example, are hot in the fourth degree;
those which provoke sweat abundantly, and thus “cut tough and compacted
humours” (Culpepper) are hot in the third degree. Opium was cold in the
fourth degree, and therefore should only be given alone to mitigate
violent pain. In ordinary cases it is wise to moderate the coldness of
the opium by combining something of the first degree of cold or heat
with it.
An amusing illustration of the reverence which this doctrine of the
temperatures inspired is furnished by Sprengel in the second volume
of his History of Medicine. Dealing with the Arab period, he tells us
that Jacob-Ebn-Izhak-Alkhendi, one of the most celebrated authors of
his nation, who lived in the ninth century, and cultivated mathematics,
philosophy, and astrology as well as medicine, wrote a book on the
subject before us, extending Galen’s theory to compound medicines,
explaining their action in accordance with the principles of harmony
in music. The degrees he explains progress in geometric ratio, so
that the fourth degree counts as 16 compared with unity. He sets out
his proposition thus: _x_ = _b_^{_n_-1}_a_; _a_ being the first, _b_
the last, _x_ the exponent, and _n_ the number of the terms. Sprengel
has pity on those of us who are not familiar with mathematical
manipulations, and gives an example to make the formula clear.
Medicament. Weight. Hot. Cold. Humid. Dry.
Cardamoms ʒi 1 ½ ½ 1
Sugar ʒii 2 1 1 2
Indigo ʒi ½ 1 ½ 1
Myrobalans ʒii 1 2 1 2
--- ----- ----- --- ---
ʒvi 4½ 4½ 3 6
This preparation therefore forms a mixture exactly balanced in hot
and cold properties, but twice as dry as it is humid; the mixture is
therefore dry in the first degree. If the total had shown twelve of
the dry to three of the humid qualities, it would have been dry in
the second degree. When it is remembered that in addition to these
calculations the physician had to realise that drugs adapted for one
part of the body might be of no use for another, it will be perceived
that the art of prescribing was a serious business under the sway of
the old dogmas.