This great clinical textbook enumerates a concise number of essential formulas which are highly effective in clinic and demonstrates not only the ingredients, functions, indications and explanation of each classical formula, but also describes their uses by modifying the ingredients and dosages. It also provides an explicit description of the relationship between several groups of formulas, understanding the ingredients, rules of modification, and clinical applications. The 8 main formulas include: Gui Zhi Tang (Cinnamon Twig Decoction), Ma Huang Tang (Ephedra Decoction), Xiao Chai Hu Tang (Minor Bupleurum Decoction) Er Chen Tang (Two-Cured Decoction), Si Ni Tang (Frigid Extremities Decoction), Si Jun Zi Tang (Four-Gentleman Decoction), Si Wu Tang (Four-Substance Decoction), and Liu Wei Di Huang Tang (Six-Ingredient Decoction with Rehmannia).