Humours and Degrees.
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 = bn‑1a; 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.