楞伽阿跋多羅寶經註解 1.683

1.683

空空者，空之又空之謂也。空之又空，能空之觀也；妄想自性處，所空之境也。由凡夫於此執著妄想自性，故如來說空、無生、無二、離性離相之法也。空有廣略故，諸經教所說空義非一，此經但說七種，乃赴一時之機，如應病與藥也。具見下文。

'Emptiness of emptiness' means emptying that which is already empty. Emptying that which is already empty is the contemplation that can empty; the locus of the imagined svabhāva is the object to be emptied. Because ordinary people cling to the imagined svabhāva here, the Tathāgata teaches the dharmas of emptiness, non-arising, non-duality, and freedom from nature and characteristics. Emptiness can be broad or brief, so what is taught regarding the meaning of emptiness in the sūtras and teachings is not just one; this sūtra only teaches seven kinds, adapting to the capacity of the moment, just as prescribing medicine according to the disease. The details are seen below.