Wu Collection, Lower Volume Radical: Cave (xué) Qiao Kangxi strokes: 18 Page 869, Entry 03 Pronounced qiao (falling tone). According to the Explaining and Analyzing Characters (Shuowen Jiezi), it refers to a hole or opening. Book of Rites (Liji), Rites of the Operational World (Liyun): The earth maintains the yin energy, which manifests as openings in mountains and rivers. The commentary explains that this means the earth holds yin energy within the mountains and rivers, which serves as a means for the earth to exhale and inhale its breath. Rites of Zhou (Zhouli), Offices of Heaven (Tianguan): Account for the changes of the nine openings. The commentary states that there are seven yang openings and two yin openings. The sub-commentary explains that the seven yang openings are located on the head and are visible, while the two yin openings are located on the lower part of the body and are not visible. Furthermore, all substances that are slippery or smooth can be used to nourish these openings. The sub-commentary explains that anything with slippery qualities can move freely and open up spaces like orifices, and thus can be used to nourish them. Classic of Mountains and Seas (Shanhaijing): The people of the Chest-Pierced Kingdom have openings in their chests. Textual Research: In the Book of Rites (Liji), Rites of the Operational World (Liyun), the original text reads that the earth holds openings within mountains and rivers. We have carefully added the character for yin after the word for earth to match the original text.