For those who are advanced in age, with depleted essence and weak constitution, finding it difficult to procreate, plants and trees, being insentient matter, cannot provide tonification. Therefore, it is appropriate to use the aforementioned animal-derived substances as medicinal ingredients. This is because they are derived from blood and qi, making them easier to assimilate for tonification purposes.

Preface: Using food and herbs to extend life is merely the superficial aspect of the art of longevity. True longevity is achieved by reducing desires until reaching a state of desirelessness. If desires are not extinguished, suffering will not be extinguished; if suffering is not extinguished, life will inevitably cease. Even if Taiyi were to prescribe formulas, Shenhuang to evaluate medicines, Xuanyuan (Yellow Emperor) to inquire personally, or Guangchengzi to carefully prepare them, such efforts would only lead to premature death and disaster, rather than extending life. How could one hope to prolong their years?

Dihuang (Rehmanniae Radix Preparata) has a rich flavor and belongs to "yin within yin"; therefore, it can nourish yin blood. It must be steamed nine times to ensure its aroma and flavor become pure and harmonious.

Huangjing (Polygonati Rhizoma) has an aroma and flavor similar to that of Dihuang, thus it can generate yin essence. The Zhenren (True Person) stated: Long-term consumption can shed old skin, beautify the complexion, darken gray hair and beard, and promote longevity and life extension.

(Those not exposed to wind and sunlight are of superior quality.)
Pine trees endure for millennia without shedding leaves and remain un-withered despite frost and snow because their interior is rich in resin/oil. Those who practice ingestion therapy use it, hoping it will make their bodies as resilient as pine and extend their years.

Take twenty jin of Baiyunmu (Mica), break it into thin flakes. Use eight dou of dew water to create a solution, dividing half of it to wash the mica twice. Then take another two dou of dew water, add ten jin of Mangxiao (Natrii Sulfas), and soak the mica in this mixture for twenty days. Dry it in the shade, then rub it in a wooden or stone mortar until extremely fine, yielding five dou of high-quality powder; discard the remainder. For every one dou of good powder, mix with two jin of Yami (Cliff Honey), stirring until it resembles porridge. Place the mixture into a raw bamboo tube, scrape off the green outer layer of the bamboo, seal the mouth with lacquer, and bury it six chi deep underground. After forty days in spring and summer, or thirty days in autumn and winter, retrieve it; it should have transformed into a substance resembling Zexie (Alismatis Rhizoma). If cavities remain undissolved, bury it for another thirty days before retrieving. To consume, first drink one he of water, then take one he of the medicine, mix well, and ingest. Take three times daily.
Sun Taoren (Master Sun Simiao) said: After taking this medicine for ten days, urine turns yellow, indicating the prior treatment of labor-qi and wind-rash conditions. After twenty days, cold accumulations in the abdomen dissipate. After thirty days, decayed teeth regenerate. After forty days, one becomes immune to wind and cold. After fifty days, all diseases are eliminated, the complexion becomes increasingly youthful, ensuring longevity and life extension.