Revolutionary theories were transforming the physical sciences and it seemed possible that the medicine would also establish a new theoretical foundation. Eminent physicians developed elaborate theories about the working of the human body, but such theories generally had little to do with the practical details of patient care. Thomas Sydenham, who has been honored as the English champion of clinical or bedside medicine, provides an instructive example of a physician who recognized the growing tension between medicine as science and medicine as the care of the sick. Thomas Sydenham was the epitome of the clinician, that is, a doctor who was devoted to carefully observing and caring for his patients, rather than debating medical theories or conducting anatomical research. Although nutrition is generally regarded as a twentieth-century science, the belief that health and longevity depend on regulating the consumption of food and drink is one of the most ancient and universal principles of medical theory.