大方廣圓覺修多羅了義經略疏 2.2

2.2

第三、深究輪迴之根者，謂窮其展轉根元，推其差別種性故，於中文四：初，三：今初。

Third, investigating deeply the root of saṃsāra means thoroughly plumbing its evolving roots and sources, and deducing its distinct gotras. Within this, the text has four parts; the first has three, and this is the first.