妙法蓮華經玄義 8.45

8.45

又心是繩墨，若觀心得正語，離邪倒說。觀心正則勉邪行，心無見著，則入正理。事行如繩，理行如墨，彈愛見木，成正法器也。

Furthermore, the mind is the marking-cord: if one contemplates the mind, one attains correct speech and departs from perverse and inverted expositions. When contemplation of mind is correct, one avoids perverse practice; when the mind is free from view-attachments, one enters the correct principle. Concrete practice is like the cord, and principle practice is like the ink: snapping them against the wood of attachment and views, one forms a vessel of the true Dharma.