大乘起信論別記 1.91

1.91

言「若離不覺則無真覺自相可說」者，是明所說真覺必待不覺，若不相待則無自相。待他而有亦無自相，自相既無，何有他相？是顯諸法無所得也。如下文言「當知一切染法淨法皆悉相待，無有自相可說。」《智度論》云「若世諦如毫釐許有實者，第一義諦亦應可實。」此之謂也。

The statement "If separated from non-enlightenment, there is no self-characteristic of true enlightenment that can be expounded" explains that the expounded true enlightenment necessarily depends on non-enlightenment; if they did not depend on each other, there would be no self-characteristic. What exists in dependence on another also has no self-characteristic; since the self-characteristic is absent, how could there be the characteristic of another? This reveals that all dharmas are ungraspable. As the text below says: "One should know that all defiled dharmas and pure dharmas are mutually dependent, having no self-characteristic that can be expounded." The Mahāprajñāpāramitopadeśa says: "If the conventional truth were real even to the slightest degree, the ultimate truth would also have to be real." This is what it means.