摩訶止觀 3.51

3.51

次、明觀相。觀有三：從假入空，名「二諦觀」；從空入假，名「平等觀」；二觀為方便道，得入中道，雙照二諦，心心寂滅，自然流入薩婆若海，名「中道第一義諦觀」。此名出《瓔珞經》。

Next, explaining the characteristics of contemplation. Contemplation has three: entering emptiness from the provisional is called the 'contemplation of the two truths'; entering the provisional from emptiness is called the 'contemplation of equality'; taking the two contemplations as the expedient path to attain entry into the middle way, illuminating both truths simultaneously, mind-moment after mind-moment extinguished and quiescent, naturally flowing into the ocean of sarvajñā, is called the 'contemplation of the middle way, the supreme truth'. These names come from the Yingluo jing.