首楞嚴義疏注經 8.65

8.65

持戒清淨，遠離貪婬，故名初乾，即斷煩惱障也。乾義有二：一欲盡故曰乾；二但慧故曰乾。今即初義，根境不偶，由三昧力返流全一，破所知也。

"Holding the precepts purely and staying far from greed and lust, it is called initial dryness; this is the cutting off of the affliction obstacle. 'Dry' has two meanings: first, called dry because desire is exhausted; second, called dry because there is only wisdom. Here it is the first meaning: faculties and objects do not match, and by the power of samādhi one reverses the flow to unite in oneness, shattering the obstacle of the knowable."