Choleric

Yellow bile is the humour of the choleric temperament, and in Galenic physiology it was a residue separated out while blood was being made in the liver, and collected in the gall bladder. Its qualities are hot and dry, which is what places it with fire among the elements, with summer among the seasons, and with young adulthood among the ages of life.

Of the four humours, yellow bile is the one that mapped most easily onto something a physician could actually see. It was visible in vomit and in the yellowing of the skin, and fevers were understood as its excess, which is why the choleric complexion was thought the one most liable to acute and violent illness rather than to long decline. That observational anchor gave the humour a plausibility black bile never had.

The therapeutic logic ran as it did for blood. An excess of a hot dry humour called for cooling and moistening: a diet of cold and wet foods, rest, and preparations chosen for the opposite qualities. Whole pharmacopoeias were organised on this principle, with each simple assigned a quality and a degree of intensity, so that a remedy could be selected to answer a complexion rather than a named disease. Culpeper's English herbal, written in the seventeenth century for readers who could not afford a physician, still assumes exactly this framework and expects its readers to know their own complexion.

Choler is the one humour whose name became an ordinary English word for anger. To be choleric is to be quick to rage, and the sense has been stable for centuries; bilious carries the same freight, and to say that someone has a jaundiced view of a thing is to speak the humoral theory without knowing it.

The portrait the older writers drew was wider than temper. The choleric complexion was lean rather than full, quick in movement and in speech, bold, ambitious, impatient of contradiction and impatient of delay. It was held to make good soldiers and difficult subordinates. Astrological medicine gave it to Mars, whose traditional qualities are likewise hot and dry, and a chart with Mars strongly placed was read as inclining the native to precisely this set of traits.

Because choler is quick, it was also thought to burn itself out. An excess of a hot humour corrects faster than an excess of a cold one, which is why the choleric person in these accounts is furious and then finished, as against the melancholic person who broods and does not recover. That contrast between a temper that flares and one that settles is the most durable thing in the whole scheme. It survives in ordinary talk about personality long after the fluids it was built on were abandoned by medicine, and it is the reason the four names remain usable when almost nothing else in Galenic physiology does.

Sources On the Affected Parts / On My Own Opinions (Galenic corpus, reference synthesis)Galen; reference synthesis by Wikipedia contributors with Christian AstrologyWilliam Lilly