Acharya Prashant explains the distinction between 'Sat Buddhi' (pure intellect) and 'Ku Buddhi' (dull or distorted intellect) as described in the Ashtavakra Gita. He defines 'Buddhi' as the guiding force that moves the mind between states. A person with 'Ku Buddhi' may technically perform all the right spiritual actions, such as meditating on the Atman as pure and one, yet they remain deluded and unhappy. This occurs because they place their own self-image and preservation above the truth. For them, the truth is a high priority, but it remains secondary to their ego. Consequently, they only accept a version of the truth that is compatible with their existing identity, leading to perpetual delusion.