大乘起信論義記 3.36

3.36

Fifth, regarding the perceiving mind: this is the evolving consciousness among the five consciousnesses and the mark of the perceiver among the three subtle [marks], where fundamental avidyā stirs [the mind] to make it able to perceive. As the text above says, 'Relying on the stirred mind, it becomes able to perceive.' On the ninth ground, one properly knows the ten kinds of dense forests of sentient beings' mental operations, hence it is termed 'mastery over mind'. This is mastery with respect to others' minds. Furthermore, because one personally attains the four unhindered cognitions, the obstructed cognizer can never arise again, hence it is said that 'it can be separated from by relying on the ground of mastery over mind'.