Acharya Prashant defines madness or insanity as a state where the natural flow of the mind, intellect, and senses is obstructed by foreign elements. He explains that the term 'Vikshep' refers to an interference or obstacle in this natural flow. Madness is not just a permanent clinical condition but occurs whenever one fails to see what is present or imagines what is not there. This happens because the mind and senses lose their smooth, rhythmic flow when something unnatural enters the system. He points out that most people are never fully awake or attentive; instead, they rely on memory, beliefs, and imagination as substitutes for actual presence and intelligence.