Spleen qi governs ascending, while stomach qi governs descending. The digestion of food primarily involves the coordination of the spleen and stomach in the process of ascending lucidity and descending turbidity. The spleen is yin earth, and the stomach is yang earth. The dryness of the stomach and the dampness of the spleen work in harmony to digest food. The spleen governs the rise of the clear, enabling the upward transport and transformation of the essence of water and grain. Stomach qi, on the other hand, descends smoothly, pushing the partially digested food (including food residues) downward, which is referred to as "descending turbidity." This function complements the spleen's role of "ascending lucidity." If stomach qi fails to descend, symptoms such as vomiting may occur.