妙法蓮華經玄義 7.114

7.114

因果等法幽微難曉，故約此指彼；眷屬是人，召證為易，或可將本人示迹人，或將迹法顯本法，互現意耳。

Dharmas such as cause and result are profound, subtle, and difficult to comprehend; hence one relies on this to point to that. The retinue consists of persons, who are easy to summon as witnesses. Alternatively, one may take original persons to reveal trace persons, or take trace dharmas to reveal original dharmas; the intention is to manifest them mutually.