Herbert Shelton wrote 40 books over his 60-year career in health education and "natural hygiene." He supervised over 30,000 fasts of chronically ill and terminal patients, losing only three. Shelton's teachings on fasting inspired Ghandi. Harvey and Marilyn Diamond said of Shelton: "A man of astounding intelligence and understanding, Dr. Herbert Shelton was the greatest health oracle of the 20th century."