Acharya Prashant explains the relationship between thoughts and tendencies, using the example of a child's liking for sugar. He clarifies that while thoughts may appear original or varied—such as greed at a shop, anger at a party, or fear after a medical report—they all originate from an underlying tendency called 'Vritti'. These tendencies are like deep-seated habits or biological dictates that act as a 'mother' or a teacher giving dictation, producing different thoughts depending on the situation. He emphasizes that thoughts are not original but are dictated by the body's tendencies and past experiences.