仁王護國般若波羅蜜多經疏 2.125

2.125

解曰：言四大者，地水火風，謂堅濕等，至下當悉。起必俱有，無色處無。實相非，彼故云不住。體遍四大，故云不離。從此第五六處即離。

Explanation: As for the "four great elements", earth, water, fire, and wind, they refer to solidity, moisture, and so forth, as will be explained in full below. When they arise, they must exist together, and they are absent in the formless realm. The real mark is not them, hence it is said to "not abide". Its substance pervades the four great elements, hence it is said to "not be separated". From here is the fifth, identity and separation regarding the six sense spheres.