During the Southern Song Dynasty, there was a pharmacologist who authored a three-volume work titled "Processing Theory," which documented 17 methods of drug preparation including roasting, grilling, frying, calcining, sun-drying, and dew exposure. The original text has been lost, but its contents have been preserved through inclusion in various materia medica compilations throughout history. Some of these preparation methods are still in use today. The currently circulated "Leigong Paozhi Lun" is a reconstructed version compiled by the modern scholar Zhang Ji.