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The herbs recorded in this collection number more than seven hundred and twenty, an increase of two-fifths over the *Bencao Beiyao* (Essentials of Materia Medica). Regarding commonly used substances in the world, they are almost fully covered. However, the properties of medicines often vary slightly with time and place. Therefore, Tao Hongjing once said: "The origins of all drugs have specific regions." The miscellaneous drugs currently available mostly come from nearby areas; how can their qi force and nature/properties be similar? Li Dongyuan also stated: "If the proper region is lost, the nature and flavor may differ; if the proper season is lost, the aroma and essence will not be complete." Thus it is known that ancient scholars already considered this with great caution. How much more so today, when the places of production have undergone many changes, compounded by people's manners being less upright than in antiquity and various methods of forgery existing. Unless one distinguishes and examines with precision and detail, how can one expand upon previous knowledge and instruct future generations? Wang Ang's *Bencao Beiyao* (Essentials of Materia Medica) compiled statements from various sources, achieving great merit, but correcting errors and verifying variants was not its strength; this is indeed a deficiency of this book. [I], Wu Yiluo, possess shallow learning. In this re-edition, whatever I have personally experienced and truly know to be correct has been carefully revised. The rest are tentatively left as they were. I only hope that scholars within the seas who are profound in the investigation of things (Gewu Zhizhi) will each offer new insights to rectify my shortcomings. This is truly my fortune, and not merely my personal fortune.
Written again by Wu Yiluo on the third day before the Winter Solstice in the mid-winter month of the Ding-Chou year of Qianlong [1757].