The Buddha tells the monks that before his Enlightenment he had thought, “What is the satisfaction (assāda), what the danger (adīnavā), and what the escape (nissaraṇa) from forms?. What is the satisfaction … of feelings? … of perceptions? … mental formations? … consciousness?” Then I considered, “Whatever is the happiness and pleasure that arises dependent on forms, that is the satisfaction of forms. That form’s impermanence (anicca), unsatisfactoriness (dukkha), and instability (vipariṇāmadhamma) is its danger. The removal of the desire and lust for forms was the escape.” So too, regarding feelings, perceptions, mental formations, and consciousness.

“Until I had thoroughly understood the satisfaction, danger, and escape regarding these five aggregates I did not declare that I was Fully Enlightened. When I had thoroughly understood them, then I knew that my liberation was unshakeable and that this would be my final existence.” (S.iii.27–29)