首楞嚴義疏注經 9.35

9.35

淨空，即靜樂也。定心轉勝，引發此樂令其無涯。樂既無涯，方是成就淨樂之義，此則名為徹意地樂。遍身輕安名無量淨。

"Pure emptiness" is quiescent bliss. The mind of meditative absorption becomes increasingly superior, giving rise to this bliss and making it boundless. Once the bliss is boundless, only then is it the meaning of accomplishing pure bliss; this is called bliss pervading the ground of mind. Boundless pliancy throughout the body is called Limitless Purity.