成唯識論演祕 3.386

3.386

因闕之義，略有兩釋：一云種子名因，彼無種故，故名因闕。二云因者所以之義，彼無生香等道理故。

Regarding the meaning of 'the cause is lacking,' there are briefly two interpretations: One says that seeds are called 'cause'; because they lack those seeds, it is called 'cause lacking.' The second says that 'cause' means 'reason'; because they lack the rationale for generating fragrances and the like.