摩訶止觀 7.42

7.42

If one contemplates the mind in the dharmatā as a dharma arisen from causes and conditions, one kind is all kinds, and one mind is all minds. Because the dharmatā is empty, all minds are one mind, and one emptiness is all emptiness. Because the dharmatā is provisional, one mind is all minds, and one provisionality is all provisionality. Because the dharmatā is middle, it is neither one nor all, neither empty nor provisional while simultaneously illuminating emptiness and the provisional. The minds of the nine dharmadhātus are also like this. This is called the “mindfulness of mind” (cittasmṛtyupasthāna).