In the past, a weak stomach and poor digestion was recognised as one of the diseases of philosophers, scholars and the learned. There was a finite quantity of vital spirits in the body: if they were called on to power digestion, they would not be available for the demands of deep thinking, and, conversely, philosophising interfered with the stomach’s duties. In the late 15th century, Ficino wrote that ‘it is bad to strain the stomach with food and drink, and worst of all, with the stomach so strained, to think difficult thoughts,’ and early in the 18th century the author of a treatise on occupational diseases noted that ‘all the men of learning used to complain of a weakness in the stomach.’