說無垢稱經疏 5.696

5.696

贊曰：四界者：地水火風。空者，空理義云：謂真空性。應理義者，所執即空無，真如是空性，准前取蘊與空二解。前中後際，去來今也。性皆無倒，即真理故。

The Commentary says: The 'four realms' are earth, water, fire, and wind. 'Space': the perspective of the principle of emptiness says this refers to true empty nature. The rational perspective states that the imagined is empty non-existence, and tathatā is the nature of emptiness, following the previous two explanations of the appropriated aggregates and emptiness. The prior, middle, and subsequent limits are past, future, and present. Their natures are all uninverted, because they are the true principle.