《晋书·志·第四章》
天上有北斗七星，地有七层地表；天有四隅，地有四条大河东流入海。
天有七星，地有七表；天有四维，地有四渎。
There are seven stars in the Big Dipper in the sky, and there are seven layers of earth on the ground; the sky has four corners, and there are four great rivers on the ground that flow east into the sea.