楞伽阿跋多羅寶經註解 2.21

2.21

前觀內心，此修外觀，此之二觀修乃隨宜，未必俱用。言外性非性者，了外法之性非自、他等四性而生也，謂陽焰、夢幻等性是也。此一切法由無始妄習為因，故皆不實如焰、夢等，是為善觀外性非性也。

The previous contemplation was on the inner mind; this cultivates the external contemplation. The cultivation of these two contemplations accords with what is appropriate, and they need not necessarily both be employed. 'Contemplating external existents as non-existent' means understanding that the nature of external dharmas is not produced from the four natures—self, other, and so forth; that is, their nature is like a mirage, a dream, an illusion, and so forth. Because all these dharmas have beginningless false vāsanā as their cause, they are all unreal like mirages and dreams; this is skillfully contemplating external existents as non-existent.