大般涅槃經疏 31.6

31.6

初破空是光明者，數家亦謂二十一色空屬明色。於中又二：先牒執、次破之。文云亦可說言虛空是常者，具足應云亦不可說是常。文中略故，而無不字。虛空雖無，不可說常，終是無常。但此外道不解空義，云空是色。乃是空中容於光色，何得乃言空是色耶？言亦可者，應言不可，語略故爾。

First, refuting [the view that] space is light: The Abhidharma masters also claim that among the twenty-one types of form, space belongs to visible forms of light. In this there are also two parts: first, citing the attachment; second, refuting it. The text states: "It can also be said that space is permanent"; in full it should say, "It can also not be said that it is permanent." Because the text is abridged, it lacks the word "not." Although space is non-existent, it cannot be said to be permanent, for it is ultimately impermanent. It is just that these non-Buddhists do not understand the meaning of space and say that space is form. It is rather that space accommodates the form of light; how could one go so far as to say that space is form? Where it says "can also," it should say "cannot"; this is merely an abridgement of phrasing.