Ling Zhi Reishi, also known as "Mushroom of Immortality", has long been revered in Chinese medicinal history as a "miracle herb". It was once believed to enhance youth and longevity, if taken over long periods of time. The Four-Canons of Seng-Nung, a famous herbal medicine book written in 2838 B.C., records Reishi as the most valuable of all "superior" herbs (followed by ginseng).