摩訶止觀 3.113

3.113

何故「性」屬生善，「行」屬對治破惡耶？若通論，性善有冥有顯，行惡亦有冥有顯。今從義便，善是冥伏，惡是彰露。如佛未出時，三乘善根冥伏不現，故言善性冥也。若聞三諦，此善發生，故知種種性應屬生善，可對為人悉檀也。

Why does "nature" pertain to generating good, while "action" pertains to counteracting and destroying evil? Speaking generally, the nature's goodness has both hidden and manifest aspects, and the evil of action also has both hidden and manifest aspects. But here, following the convenience of the doctrinal meaning, good is hidden and submerged, while evil is exposed and patent. For instance, before the Buddha appeared in the world, the good roots of the three vehicles lay hidden and submerged, not manifested; thus it is said that the good nature is hidden. When hearing of the three truths, this goodness is aroused and generated; hence we know that various kinds of nature should pertain to generating good, which can be correlated with the person-specific siddhānta.