俱舍論疏 20.67

20.67

論「如世間說至其義亦應爾」，喻合也。如世間說：有燈前日無，有燈昨日無。說有燈無時，豈有燈耶？爾時無燈而言有燈，故知有聲非唯顯於有法。有燈已滅，亦准於此。既言已滅，即是無燈而言燈，故知於無說有。

The Śāstra says: "Just as in worldly conventions it is said... its meaning should be understood likewise": this brings together the simile and its application. Just as in worldly conventions it is said, 'There is a lamp that was absent the day before', 'There is a lamp that was absent yesterday'—when saying 'there is an absence of a lamp', how could there be a lamp? At that time there is no lamp, yet one says 'there is a lamp'; hence we know that the word 'exists' does not solely indicate an existing entity. 'There is a lamp that has already been extinguished' should also be understood accordingly. Since one says 'already extinguished', this is non-existence of a lamp, yet one speaks of a lamp; hence we know that one speaks of 'existence' with respect to non-existence.