Kenelm Digby

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Sir Kenelm Digby (1603–1665) was an English courtier, diplomat, privateer, and natural philosopher who moved easily between the experimental science of his day and the older world of alchemy and sympathetic cure. He is remembered most for the “powder of sympathy,” a remedy he claimed could heal a wound by treatment applied not to the injury but to the weapon or the bloodied cloth that caused it.

His life reads as a sequence of improbable turns. His father, Everard Digby, was hanged and quartered for his part in the Gunpowder Plot of 1605, when Kenelm was two. The son nonetheless rose at court, was knighted by James I, and in 1628 fitted out ships and won a naval action against the French and Venetians at Scanderoon in the eastern Mediterranean. He married Venetia Stanley, a celebrated beauty whose sudden death in 1633 sent him into seclusion and a long programme of chemical experiment. A Catholic by birth who conformed for a time, then returned to Rome, he spent stretches of his life abroad, corresponded with Descartes, Hobbes, and Fermat, and was among the original fellows when the Royal Society received its charter in 1662.

The powder of sympathy was the doctrine that made and dogged his name. Digby held that a wound could be treated by applying a preparation — vitriol, calcined and dissolved — to a cloth stained with the patient’s blood, or to the offending blade, while the injury itself was merely kept clean and bound. He delivered a public lecture on it at Montpellier in 1657, and explained the effect by the mechanical philosophy he favoured: atoms of blood and vitriol, drawn through the air by the sun, carried the cure from cloth to flesh. The salving of weapons rather than wounds was older than Digby, running back through Paracelsus, and contemporaries such as Robert Fludd had argued it on frankly occult grounds. What is distinctive in Digby is the attempt to give an avowedly corpuscular, mechanical account of an action at a distance that later medicine would file among the cures that worked, if at all, by leaving the wound alone.

His interests extended past the powder. He kept a laboratory, pursued the transmutation of metals, and wrote on the “vegetation of plants,” reporting experiments that touched on what would later be understood as the role of air in plant growth. He was also a serious collector of books and manuscripts; the mathematical and alchemical library of the Oxford scholar Thomas Allen passed to him and was given on to the Bodleian.

Scholarship has tended to read Digby as a transitional figure rather than a crank — a man whose mechanical philosophy and whose belief in sympathetic action sat side by side without strain, in the decades before the two were sorted into science and superstition. The powder kept his name alive long after the theory fell, less for what it healed than for what it shows: how thin, in the mid-seventeenth century, the line between the new natural philosophy and the old magic still was.

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