大般涅槃經義記 3.366

3.366

Next is the third part, Kāśyapa's praise of the profundity. 'Buddha-nature is inconceivable' praises its nature as the cause; 'the marks and signs are inconceivable' praises the resulting fruition. In accordance with the marks, there seem to be distinctions, but in reality they are the true nature; therefore they are inconceivable.