Chou Collection, Upper Volume. Radical: Enclosure (wéi). Character: Xin. Kangxi stroke count: 6. Page 216, Entry 27. The ancient form is written as Xin. According to the Extensive Dictionary of Sounds and Meanings (Guangyun), it is pronounced xin. According to the Collection of Sounds and Meanings (Jiyun), it is pronounced xin, with a sound identical to xin. The Explanation of Simple and Compound Characters (Shuowen Jiezi) defines it as the skull plate at the point where the cranial bones meet. The character shape is a pictograph. Wei Xiao states that this refers to the fontanelle. When a fetus is in the mother's womb, all orifices are still closed, and only the umbilical area allows for internal circulation, with the fontanelle facilitating this breath; the bones at this location are the only ones not yet closed. After birth, the orifices open, the mouth and nose intake air, the tailbone expels air, and the fontanelle gradually closes; this is the passage for the rising and falling of yin and yang. Medical texts record that the center of the crown of the head where the hair swirls is the Hundred Meetings point, one and a half inches in front of the Hundred Meetings point is the Front Vertex point, and three inches in front of the Hundred Meetings point is the fontanelle. Additionally, according to the Collection of Sounds and Meanings (Jiyun), it is pronounced xin (rising tone). It is also pronounced si. The meanings are the same.