The Niju Kun are Funakoshi's Twenty Precepts, written to help the student understand how they should conduct themselves in karate, and in everyday life. Each of the principles is explained in detal in 'The Twenty Guiding Principles of Karate' by Gichin Funakoshi.
1. Karate is not only dojo training.
2. Don't forget that Karate begins with a bow and ends with a bow.
3. In Karate, never attack first.
4. One who practices Karate must follow the way of justice
5. First you must know yourself. Then you can know others.
6. Spiritual development is paramount; technical skills are merely means to the end.
7. You must release your mind
8. Misfortune comes out of laziness.
9. Karate is a lifelong training.
10. Put Karate into everything you do.
11. Karate is like hot water. If you do not give heat constantly it will again become cold.
12. Do not think you have to win. Think that you do not have to lose.
13. Victory depends on your ability to tell vulnerable points from invulnerable ones.
14. Move according to your opponent.
15. Consider your opponent's hands and legs as you would sharp swords.
16. When you leave home, think that millions of opponents are waiting for you.
17. Ready position for beginners and natural position for advanced students.
18. Kata is one thing. Engaging in a real fight is another.
19. Do not forget (1)strength and weakness of power, (2)expansion and contraction of the body, (3)slowness and speed of techniques.
20. Devise at all times.