na ca pramāṇahetutvād upacāreṇa kalpanā yuktā, yato nīrūpasya sarvasāmarthyavirahalakṣaṇatvān na hetutvasambhavo yuktaḥ /
And it is not proper to make assumptions based on the figurative notion of being a cause of valid cognition, since what is featureless, being characterized by lack of all capacity, cannot properly be considered to have causal efficacy.