Acharya Prashant explains that understanding is fundamentally different from thinking. He asserts that many people are enslaved by their brains, mistakenly believing that understanding is a matter of thought. He clarifies that in a moment of true attention and understanding, thoughts cannot exist. To illustrate the progression of the mind, he outlines four stages: incapacity for thought, thought, thinking, and understanding. He describes 'thought' as a subconscious, automated movement determined by conditioning and the environment, where one acts as a slave to external stimuli. 'Thinking' is defined as a partly conscious process where one applies thought to a problem, yet it is still governed by past knowledge.