首楞嚴義疏注經 1.523

1.523

清淨，揀異妄染。妙淨明心，即三德具足，靈鑒無昧也。雖能隨緣成一切法，而一切法不能變動，若變動者即無諸法，以不變故為諸法性。如鏡現像不為像變，若為像變，則不能現一切諸像，以不變故為像所依。此亦如是，故云性一切也。豈得妄想不實，真亦無體，故此責云而自無體也。

'Pure' sets it apart from false defilement. 'Wondrously pure, luminous mind' means it is replete with the three virtues, spiritually inspecting without darkness. Although it can follow conditions to become all dharmas, all dharmas cannot change it; if it were changed, then there would be no dharmas, and because it is unchanging, it serves as the nature of all dharmas. Just as a mirror displaying images is not changed by the images—if it were changed by the images, it could not display all the images; because it is unchanging, it serves as that upon which images rely. This is also like that; hence it says 'the nature of all.' How could it be that while false thoughts are unreal, the true also lacks substance? Therefore he rebukes this, saying, 'itself lack a substance.'