Scurvy: how a surgeon, a mariner, and a gentleman solved the greatest medical mystery of the age of sail

Physicians performed great philosophical back-flips and other mental acrobatics in a vain effort to reconcile common sense with their theoretical constructs .... Seventeenth- and early-eighteenth-century medicine was based not on scientific method or an experimental approach but on theoretical reconciliation. Fortunately for many patients, the humoral concept of medicine declined throughout the eighteenth century as physicians began studying the actual workings of internal organs and the circulatory system in greater detail. By the nineteenth century, medicine had returned to scientific ground, with an emphasis on observation and experiment rather than hypothesis and a desire for theoretical harmony.

[Meanwhile] the world of medicine was extraordinarily confused, with a great variety of physicians each offering his own personal variation on the humoral theory. To make universal sense of it is nearly impossible; indeed, the theories of many physicians were contradictory. With the layers of speculation building upon each other like the skins of an onion, and physicians tweaking their predecessors’s theories to accommodate glaring inconsistencies ... cures became ever more fanciful and bewilderingly disconnected from reality.

In the quest for a universal theory of disease, much common sense was thrown aside and replaced with learned posturing. People, then as now, are inclined to dismiss trifling inconsistencies in their pet theories when they faithfully believe them to be correct — and perhaps more dangerous and malignant, when they believe a reputation is at stake or money is to be made. Folk wisdom has it that what we wish to be true, we readily believe.