"I found that religious visionaries such as St John of the Cross, St Augustine, Hildegard of Bingen and Julian of Norwich all recommended fasting as a way to clear the head and concentrate. Gandhi fasted in order to focus his mind. Pythagoras refused to accept anyone into his school who did not know how to fast. The Greeks intrigued me. Our religions are imports from the east where ascetic practice is normal, so I would expect to find a tradition of fasting there, but the Greeks were rationalists, the founders of western medicine. But here are Plato and Socrates fasting for mental efficiency, Plutarch advocating a day of fasting for any minor disorder, and Hippocrates saying that “to eat when you are sick is to feed your sickness”."