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All herbs and insects have their respective suitable places of origin. Their flavors and therapeutic efficacies naturally differ from the ordinary. As the proverb goes, "The environment of one region nurtures its people," which also implies that "the land of one region produces the medicines for it." Those who pay attention to health preservation desire authentic products but are often deterred by the difficulties of long journeys, preferring to collect locally available substitutes. However, they fail to realize that some medicinal materials cannot be substituted even if produced elsewhere. Substitutes may be used when there is only a slight difference in the intensity of their effects; doubling the dosage can still suffice to cure the disease. In cases where substitution is not possible, it is because the purity or impurity of their flavors differs significantly; reckless ingestion may instead harm the body. Thus, *Shennong Bencao Jing* (Divine Farmer's Materia Medica) states that although Ginseng Radix et Rhizoma (Renshen) and Astragali Radix (Huangqi) share the same indications despite different origins, Ligusticum Chuanxiong Rhizoma (Chuanxiong) and Angelicae Sinensis Radix (Danggui) have different indications due to different species, which serves as evidence. Others include Pinelliae Rhizoma Preparatum (Banxia) from Qizhou, Asari Radix et Rhizoma (Xixin) from Huayin, Bupleuri Radix (Chaihu) from Yinzhou and Xiazhou, Lycii Fructus (Gouqi) from Gansu; Corydalis Rhizoma (Yanhusuo) and Atractylodis Rhizoma (Cangzhu) from Maoshan, Dioscoreae Rhizoma (Shanyao) and Rehmanniae Radix (Dihuang) from Huaqing; Atractylodis Macrocephalae Rhizoma (Baizhu) from Shezhou, Astragali Radix (Huangqi) from Mianzhou, Ginseng Radix et Rhizoma (Renshen) from Shangdang, and Cinnamomi Cortex (Rougui) from Jiaozhi. Each gains fame due to its place of origin, hence named after the location. Superior terroir yields potent medicines, making this observation credible. Furthermore, herbs suitable for mountain valleys should not be confused with those cultivated in gardens, such as Paeoniae Radix Rubra (Mudanpi) and Paeonia suffruticosa roots; conversely, garden-cultivated herbs like Chrysanthemi Flos (Juhua) and Morus Alba Root Bark (Sangbaipipi) should not be mixed with wild ones from valleys. Regarding moistening herbs from marshes, it is not just Lysimachiae Herba (Zelan); regarding clean herbs from rocks, it is not only Acori Tatarinowii Rhizoma (Shichangpu). Although Dongbi Tu (Earth from East Wall) and various soils are minute, their use follows logical principles. Qianli Shui (Water from Thousand Li) and other waters are vast, and their decoction must be appropriate. Overall, adhering to the principles of *Tujing* (Illustrated Records) benefits the preparation of medicines. The *Book of Documents* states, "Be cautious at the beginning, plan for the end." This refers to the present context.

For roots and tips of herbs and trees, harvesting is most suitable in late autumn or early spring. In early spring, fluids begin to sprout but have not yet filled the branches and leaves; in late autumn, qi and juices descend and gather entirely in the roots. Current practical experience confirms this. Spring harvesting should preferably be early, while autumn harvesting should preferably be late, which is considered perfect. For stems, leaves, flowers, and fruits, harvesting can be done according to convenience throughout the four seasons. Harvesting young stems retains the juice; collecting ripe fruits ensures pure flavor; picking fresh leaves doubles the efficacy. Such usage in medicine is indeed exquisite, making treatments effective. For minerals, birds, beasts, insects, and fish, some can be taken at any time, while others follow seasonal rhythms, each carrying profound meaning. These are not empty words; all should be followed strictly, avoiding rash actions.