摩訶止觀 9.38

9.38

This bliss stands opposed to suffering; reproaching bliss, it then subsides, and there is also a preparatory stage. When the preparatory stage has subsided, the immovable concentration manifests, which is still the material form becoming increasingly wondrous. Not being moved by suffering or bliss, it is called the 'immovable concentration.' The state of concentration is peaceful and stable; inhalation and exhalation cease; it has the factors of neither-suffering-nor-bliss, purity of equanimity and mindfulness, and one-pointedness of mind.