大方廣佛華嚴經隨疏演義鈔 21.51

21.51

疏「真妄相循難窮初後故」者，若言先妄後真，真則有始；若謂先真後妄，妄由何生？若妄依真起，真亦非真；若妄體即真，則妄亦無始。為破始起，立無始言。始既不存，終從何立？無終無始，豈有中間？故《中論》云「大聖之所說，本際不可得。生死無有始，亦復無有終。若無有始終，中當云何有？是故於此中，先後共亦無。」真妄兩亡，方說真妄；真妄交徹，無定始終。

Regarding the commentary's statement that "because truth and delusion follow one another, it is difficult to fathom their beginning and end": if one says delusion comes first and truth comes later, then truth would have a beginning; if one says truth comes first and delusion comes later, from what does delusion arise? If delusion arises based on truth, truth is also not true; if the substance of delusion is itself truth, then delusion is also without beginning. In order to refute an initial arising, the phrase "beginningless" is established. Since a beginning does not exist, from where could an end be established? With neither end nor beginning, how could there be a middle? Therefore the Madhyamakaśāstra says: "What has been taught by the Great Sage / Is that the ultimate limit cannot be apprehended. / Saṃsāra has no beginning, / Nor does it have an end. / If there is neither beginning nor end, / How could there be a middle? / Therefore, herein, / Precedence, subsequence, and simultaneity are also nonexistent." Only when both truth and delusion are discarded can one speak of truth and delusion; truth and delusion interpenetrate, having no fixed beginning or end.