《黄帝内经·素问·本病论》
司天、在泉的阴阳属性不同，其变为疫疠之气的大小善恶，和司天、在泉失守其位的变化规律是一致的。
阴阳天地殊异尔，故其大小善恶，一如天地之法旨也。
The yin and yang attributes of the sky and the spring are different, and the size and severity of their transformation into epidemic qi is consistent with the changing law of the sky and the spring losing their positions.