The answer is the hexagram shape. Let’s explain it in detail below:
1. It is necessary for a hexagram to have a name. All sixty-four hexagrams have names. A hexagram has six lines. This hexagram is What does it mean? Each line and the whole hexagram;
2. The hexagram shape you mentioned is based on the shape of the line, which people imagined. For example, shaking up the bowl and covering the bowl express the meaning of the shape. Yes, everyone can imagine this thing by themselves;
If we want to talk about other things, each hexagram also has Xiang, Tuan, etc., yin and yang, etc.
The hexagrams in the current version of "The Book of Changes" are named Qian, Kun, Zhen, Xun, Kan, Li, Gen, and Dui.
The sixty-four hexagrams are named Qian, Kun, Tun, Meng, Need, Yi, Shi, Bi, Xiao Zhu, Lu, Tai, Fu, Tongren, Dayou, Qian, Yu, Sui , Gu, Lin, Guan, Eat, bite, peel, recover, Wuwu, Da Zhu, Yi, Da Guo, Kan, Li, Xian, Heng, Dun, Da Zhuang, Jin, Ming Yi, Jia, Jian, Jian ,, solution, loss, benefit, 夬, 夤, cui, sheng, trapped, well, leather, tripod, shock, gen, gradually, guimei, feng, lv, xun, dui, huan, festival, zhongfu, xiaogao , both economical and not economical.
Reference: Gua Baidu Encyclopedia