維摩經略疏 7.21

7.21

「又問至以空空」，次問答。「問：以何為空」者，分段變易皆有依正，云何令其同歸一空？又聲聞經明空三昧、衍十八空有空空，未知以何空故空？

From "He also asked... to empty with emptiness" onward is the next question and answer. As for "He asked: By what is it empty?": fragmented and transformative both have environmental and personal retribution; how can they be made to return together to a single emptiness? Furthermore, the śrāvaka sūtras explain the emptiness samādhi, and the Mahāyāna eighteen emptinesses include the emptiness of emptiness; it is not yet known by what emptiness it is empty.