妙法蓮華經玄義 1.116

1.116

觀心生起者，以心觀心，由能觀心，有所觀境。以觀契境故，從心得解脫故。若一心得解脫，能令一切數皆得解脫故。分別心王、心數，同起、偏起等，即是教相故。

As for the arising of contemplation of mind: using the mind to contemplate the mind, because of the mind that can contemplate, there is an objective realm that is contemplated. Because the contemplation tallies with the realm, liberation is attained from the mind. If the one mind attains liberation, it is because it can cause all mental factors to attain liberation. Distinguishing the king of the mind and mental factors, their simultaneous arising, their isolated arising, and so forth, is none other than the classification of teachings.