大乘起信論義記 3.190

3.190

若心有動非真識知者，明妄識倒知；返之即顯真照無倒。無有自性者，明妄染無體；返之即顯自性清淨心也。

"If the mind has movement, it is not true cognition" clarifies that deluded consciousness is inverted cognition; reversing this reveals that true illumination is non-inverted. "It has no self-nature" clarifies that deluded defilement has no substance; reversing this reveals the inherently pure mind.