大乘起信論義疏 1.33

1.33

問：全是，妄不是？若爾，生滅不非是，何故如是？妄者就用，生滅者就法體，隨用故成，法體真故非是生滅，故經說言「不染而染其體常住。」

Question: If it is completely true, then the false is not? If so, arising and ceasing would not be non-existent. Why is it like this?

[Answer:] The false is with respect to function; arising and ceasing is with respect to the essence of dharmas. It is formed in accordance with function, but because the essence of dharmas is true, it is not arising and ceasing. Therefore a sūtra says: "Undefiled yet defiled, its essence is permanently abiding."