John Turner sent me a link to this short article in Slate‘s “The Vault” column, discussing the mathematical side of fencing:
Girard Thibault’s Académie de l’Espée (1628) puts the art of wielding the sword on mathematical foundations. For Thibault, a Dutch fencing master from the early seventeenth century, geometrical rules determined each and every aspect of fencing. For example, the length of your rapier’s blade should never exceed the distance between your feet and the navel, and your movements in a fight should always be along the lines of a circle whose diameter is equal to your height.
The rest of his manual, geared towards gentlemanly readers who took up fencing as a noble sport, is filled with similar geometrical arguments about the choreography of swordsmanship. Thibault’s work belongs to the same tradition that produced Leonardo’s renowned Vitruvian Man.