《北史·列传·卷二十八》
十三月阳气已经降临，蛰伏在地下的虫子都已苏醒，夏代当作春天的到来。
十三月阳气已至，蛰虫皆震，夏以为春。
In the third month, the yang has already arrived, and the hibernating insects all wake up, Xia Dynasty considered this as the first day of spring.