大方廣佛華嚴經隨疏演義鈔 37.3

37.3

疏「善友是緣因而必是了」下，出其二相。善友是疎亦緣亦了，如酵暖等是酪了因亦是緣因。

Regarding the Commentary's statement, "A good spiritual friend is a contributory cause and must be revealing," and so forth: this brings out their two characteristics. A good spiritual friend is remote, being both contributory and revealing, just as yeast, warmth, and the like are both revealing causes and contributory causes for curd.