妙法蓮華經玄義 2.20

2.20

As for 'such nature', it is the nature of one's own dark share. Purely habituated to dark evil, it is difficult to alter. Just as wood contains fire and breaks forth when encountering conditions. The Mahāparinirvāṇa-sūtra says: 'Because conditioned dharmas have a productive nature, production can produce them.' This evil has the productive nature of the four destinies, so conditions can activate it. As with statues of clay or wood, although having an external appearance, inwardly they lack a productive nature, so production cannot produce them. The evil nature is not like this, hence it is said: 'such nature'.