The 20 Guiding Principles of Shotokan Karate, also known as Niju Kun, were developed by Gichin Funakoshi. 

Niju Kun

1. Karate begins and ends with courtesy and respect

2. Never strike first

3. Be on the side of justice

4. Control yourself before engaging others

5. Mental attitude is more important than technique

6. Empty your mind and be present

7. Accidents stem from lack of attention

8. Carry karate values beyond the dojo

9. Karate is a life-long endeavour

10. Bring karate into your whole life and find inner peace

11. Karate is like boiling water: without applying heat it turns cold

12. Never strive to win - instead, make sure you do not lose

13. Use the strengths and weaknesses of your opponent

14. Winning depends on the right application of softness and hardness

15. Think of hands and feet as swords

16. When you step through a door, be ready to face opponents

17. First master the karate stances, then adopt a natural pose

18. Perform kata with firmness; perform combat with fluidity

19. Apply softness & hardness, contraction & expansion, relaxation & speed

20. Be mindful, diligent and resourceful in the dojo and in life.