摩訶止觀 2.78

2.78

Now, contemplating the breath: striking the seven places, it harmonizes to produce sounds like echoes, neither internal nor external, with neither reciter nor that which is recited; examining all through the four movements, one gives rise to no receiver toward sense objects and produces no agent toward conditions; afflictions do not interrupt recitation and explanation, and thought-moment by thought-moment one flows into the great sea of nirvāṇa: this is called 'vigor' (and so on).