《文心雕龙·诔碑》
古代帝王受命，就封禅于泰山，刻石记功，所以叫碑。
上古帝王，纪号封禅，树石埤岳，故曰碑也。
In ancient times, when an emperor was ordered, he would offer sacrifices to Mount Tai and engrave his achievements on stone, which is why it was called a "bei".