成唯識論了義燈 2.142

2.142

答：但有聖法名聖性，定性所知不障輕，無姓畢竟無聖法故，彼二障名為重。

Answer: Having any noble dharma is called the noble nature; for those of determinate lineage, [the obstruction to] knowables does not obstruct [this], so it is light; those lacking lineage are completely devoid of noble dharmas, therefore their two obstructions are termed heavy.