prayogaḥ yad viśuddhakāraṇajanitaṃ tat pramāṇaṃ, yathā sannikṛṣṭārthaviṣayaṃ śuklaśaṅkhagrāhivijñānaṃ, viśuddhakāraṇajanitaṃ cedaṃ viprakṛṣṭārthaviṣayaṃ pītākāraśaṅkhāvabhāsi vijñānam iti svabhāvahetuḥ //
The formal reasoning: Whatever is produced by perfect causes is valid, just as the cognition grasping a white conch-shell as a proximate object; and this cognition appearing as a yellow-formed conch-shell relating to a remote object is produced by perfect causes - this is a reason based on essential nature.