摩訶止觀 4.180

4.180

三事合調者，三事相依不得相離，如初受胎：一、煗，二、命，三、識。煗是遺體之色；命是氣息，報風連持；識是一期心主。託胎即有三事。三事增長，七日一變，三十八七日竟，三事出生，名「嬰兒」；三事停住，名「壯年」；三事衰微，名為「老」；三事滅壞，名為「死」。三事始終不得相離，須合調也。

As for regulating the three matters together: the three matters rely on one another and cannot be separated, just as at initial conception in the womb there are: first, warmth; second, life; and third, consciousness. Warmth is the physical form inherited from the parents; life is the breath, maintained continuously by karmic wind; consciousness is the master of mind for that single lifespan. Relying on the womb, these three matters immediately exist. As the three matters increase and develop, they transform once every seven days. When thirty-eight times seven days are complete, the three matters emerge into birth and are called an 'infant'; when the three matters stay steady, it is called 'prime of life'; when the three matters decline, it is called 'old age'; and when the three matters are destroyed and perish, it is called 'death.' The three matters cannot be separated from beginning to end; they must be regulated together.