大般涅槃經義記 10.77

10.77

初中，「外道言空是光」舉他所立。「若是光」下，徵令是色。「虛空若」下，徵令無常。「是無常」下，徵為三世。「若三世」下，以是三世徵為非空。「亦可說」下，立空為常，翻破前執。「虛空是常」，便非三世乃至非色，云何外道說為光明？就其意解說空為常，未可專決，故云「亦可」。

In the first: "Non-Buddhists say that space is light" cites what the opponent posits. From "If it is light..." onward interrogates it so that it must be form. From "If space is..." onward interrogates it so that it must be impermanent. From "Being impermanent..." onward interrogates it as belonging to the three periods of time. From "If it belongs to the three periods of time..." onward, on the grounds of its belonging to the three periods of time, interrogates it as not being space. From "It may also be said..." onward establishes space as eternal, overturning and refuting the prior attachment. "Space is eternal," and thus not of the three periods of time and even not of form; how could non-Buddhists say it is radiance? Explaining space as eternal according to their understanding is not yet definitively determined, which is why it says "It may also be said."