Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
When there is pain, the animal instinct is flight-or-fight. Calm yourself down and reflect instead. The pain you are feeling is due to things being in conflict--maybe you've come up against a terrible reality, such as the death of a friend, and are unable to accept it; maybe you've been forced to acknowledge a weakness that challenges the idea you'd had of yourself. If you can think clearly about what's behind it, you will learn more about what reality is like and how to better deal with it. Self-reflectiveness is the quality that most differentiates those who evolve quickly from those who don't. Remember: Pain + Reflection = Progress.