大般涅槃經義記 6.13

6.13

此前五種就現觀空，「無始空」者更無別法，但就過去觀前五空名無始空。何不就當說無終空？准置應得，故《地持》中三世俱觀，但今為明過去之法起患根本，無始已來所執著處故須觀之。過現既空，類後可知，不就後說，無終空矣。又三世法次第相生，過為現本，現為當本，現法易觀故先觀之。現由過生，故就其本說無始空。本壞末隨，故不就後說無終空。

These preceding five kinds contemplate emptiness in terms of the present. As for 'beginningless emptiness', there is no distinct dharma; it is simply contemplating the preceding five emptinesses in terms of the past that is called 'beginningless emptiness'. Why not speak of 'endless emptiness' in terms of the future? Analytically established, it should be permissible, which is why in the *Bodhisattvabhūmi* all three times are contemplated together; but here, it is to clarify that past dharmas are the root from which afflictions arise, the locus of clinging since beginningless time, and therefore must be contemplated. Since past and present are already empty, the future may be understood by analogy; hence it does not speak of 'endless emptiness' in terms of what comes after. Moreover, dharmas of the three times arise successively: the past is the root of the present, and the present is the root of the future; present dharmas are easy to contemplate, so they are contemplated first. Because the present arises from the past, beginningless emptiness is spoken of in terms of its root. When the root is destroyed, the branch follows; therefore endless emptiness is not spoken of in terms of what comes after.