首楞嚴義疏注經 2.608

2.608

喻一真也。宴，靜。調，和。適，悅也。骸，體也。忘生，忘形也。身肢安靜，恬然暢適，而無苦樂二境相逼，忽然如其無形一般，斯蓋但以捨受相應，不覺此形之有生也。李陵云：「每一念至，忽如忘生。」法中可知。

This is a metaphor for the single true [nature]. 'Peaceful' (yan) means still. 'Harmoniously' (tiao) means balanced. 'Adjusted' (shi) means pleasant. 'Joints' (hai) means the body. 'Forgetting their living existence' means forgetting one's physical form. The limbs of the body are peaceful and still, serene, free, and comfortable, with neither painful nor pleasurable states oppressing one; suddenly it is just as if one had no physical form at all. This is simply through correspondence with sensation of equanimity (upekṣā-vedanā), not noticing that this physical form has a life. Li Ling said: 'Whenever a single thought arrives, I suddenly seem to forget my living existence.' Its meaning in the Dharma can be understood.