This article focuses on a curious manuscript treatise in the British Library, Harley MS 6940, which the learned physician Samuel Bispham composed for the English patron and horseman William Cavendish (1593–1676), most likely in the mid-1640s. Sitting somewhere between a practical medical recipe book and theoretical chymical treatise, while being peppered with traditional causal explanations and Galenic precautions, Harley MS 6940 testifies to the erosion of the entrenched dichotomy between chymical and Galenic medicine in the mid-seventeenth century. Harley MS 6940 also lays bare how a learned physician used (and taught the use of) practice to confirm and sometimes challenge his learning, offering a counterpoint to recent scholarship that underscores the learning that apothecaries used to shore up their practice. Produced at the behest of a leading Royalist who sought both to acquire techniques for distilling and fermenting herbs and to advance his knowledge of chymical conceptions of spirits, seeds, and salts, the manuscript allows us to appreciate that the chymical art animated a broader set of individuals than the historiography often implies.