金光明經文句記 2.54

2.54

Third, from "three..." downward, demonstrating that the three truths are named purity. Purity is the meaning of emptiness. What is ultimately empty must empty the three truths, so as to verify that that which can empty does not lack the threefold contemplation. Because that which can empty is also empty, this purity is also pure, being unimpeded in penetration.