天官书

One of the eight treatises of the 史记. 司马迁 held the post of Grand Historian, which also kept the calendar and watched the sky, and here he maps the heavens as an empire: the Pole Star is the seat of the Supreme One in the Central Palace, the constellations around it are his court, and planets, comets and clouds are read as omens for the realm below. 天官 means 'the offices of heaven'.

Among its omens is the line 海旁蜃气象楼台 'by the sea, the breath of the giant clam takes the shape of towers', the old explanation of mirages that lies behind 海市蜃楼.