大方廣圓覺修多羅了義經略疏 2.418

2.418

Because of previously clarifying the mind through stillness, thoughts do not arise; the mind unites with the source of stillness, its essence being non-conceptual; thus one sees that the conceptualizing consciousness is troublesome and agitating. If one were [immersed in] consciousness itself, one could not see consciousness, just as an eye does not see itself. Now, because thoughts are clarified and wisdom is revealed, one perceives consciousness.