摩訶止觀 8.33

8.33

如是觀時，追傷己過，廣愍眾生。何以故？理非明闇，以迷惑故，起苦集闇；解治法故，有道滅明。約闇故悲，約明故慈，大誓之心與境俱起。

When contemplating in this way, one retrospectively laments one's own errors and extends broad pity to sentient beings. Why is this? The principle is neither light nor darkness; yet because of delusion, the darkness of suffering and accumulation arises; and because of understanding remedial dharmas, the light of the path and cessation exists. Compassion (karuṇā) is based on darkness; loving-kindness (maitrī) is based on light; the mind of the great vow arises together with the realm.