妙法蓮華經玄義 2.20

2.20

如是性者，黑自分性也。純習黑惡，難可改變。如木有火，遇緣即發。《大經》云：「有漏之法，以有生性，故生能生之。」此惡有四趣生性，故緣能發之。若泥木像，雖有外相，內無生性，生不能生。惡性不爾，故言如是性。

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'.