金光明經文句記 4.268

4.268

初、正明空。逐一推檢不應動等者，地動則成風性，煖則成火性。《史記》曰「陽伏而不能出，陰迫而不能蒸，於是有地震。」注云：蒸，升也。冬則地中煖，故《禮》云「古者夏則橧巢，冬則營窟。」水堅故成地性，波動故成風性。貞，堅也。炭火貞則成地性，火焰動則成風性，風能持物則成地性，觸壁止則成水性。

First, directly explaining emptiness. As for "investigating one by one that it should not move, and so forth": if earth moves, it takes on the nature of wind; if it is warm, it takes on the nature of fire. The *Shiji* states: "When yang is hidden and cannot emerge, and yin presses down and cannot evaporate, an earthquake occurs." The commentary states: "Evaporate means to rise." In winter, the ground is warm inside; hence the *Book of Rites* states: "In ancient times, in summer they dwelt in nests of branches, and in winter they dwelt in earthen caves." Water being firm constitutes the nature of earth; its waves moving constitutes the nature of wind. "Zhen" means firm. Charcoal fire being firm constitutes the nature of earth; flames moving constitutes the nature of wind. Wind being able to uphold things constitutes the nature of earth; when it strikes a wall and stops, it constitutes the nature of water.