A restless state of mind that wanders away from an object while observing it is a mental state called restlessness (uddhacca). It flies away from the… - Mahasi Sayadaw

The Vammika Sutta likens skeptical doubt to a fork in the road. Say a traveler who is carrying many valuables arrives at a fork in the road; if he lingers there unable to decide which way to take, robbers may catch and possibly kill him. In the same way, a doubtful meditator who falls prey to wavering and procrastination cannot continue on with practice. He or she will then become a victim of mental defilements and be unable to escape the cycle of suffering. Only when he or she abandons doubt by noting it and uninterruptedly continues the practice can he or she be liberated from the cycle of suffering.

Doubt about the fact that insight wholesomeness consists of simply observing the presently arising mental and physical phenomena is also skeptical doubt. This doubt is so subtle that it is rarely detected but is instead mistaken for investigation. This doubt masquerades as analytical knowledge. The commentary on Netti Yuttihāra explains as follows: "Doubt appears in the guise of investigation."

Ignorance immediately knows things in an ordinary, conceptual way. Because ignorance and its accompanying mental states arise first, wrong beliefs ensue. Therefore the texts say, "Ignorance conceals the true nature of obejcts."