大方廣圓覺修多羅了義經略疏 2.348

2.348

Objects manifest from the mind and are originally one's own mind. If one adds further knowing, one becomes deluded about direct perception; thus the sūtra speaks of 'what is not an illusion becoming an illusion.' The Treatise says: 'The mind does not see the mind; if only sentiments do not arise, naturally it is like a mirror reflecting objects.' Furthermore, the mind's substance is originally aware and cognizant of itself; why must one add further knowing? Producing knowing on top of knowing is what is called 'adding.'