The concept of morality requires the karateka to live an ethical life. This involves proper behaviour in all aspects of life. The Buddhist code forbids killing, stealing, lying, etc. Instead, it preaches love for fellow man. Herein lies the code of all martial artists: one's skill to harm others should only be used for self-defense or for the preservation of justice.
Mental discipline, another core idea of Buddhism, is one of the most highly sought after rewards of all martial arts training. The Zen school is known for its emphasis on meditation, called zazen, to strengthen and discipline the mind. By controlling the mind, one can suppress desire and control emotions. The martial arts practitioner should feel no anger, no pride, no pain, no suffering of any kind. These are the major causes of violence, unhappiness, and defeat, and they must be avoided. Budo training was and is often very harsh in order to bring the individual to the boundaries of their physical limitations, and then to surpass them.
Intuitive wisdom implies that one must do, not think. When "thinking," one imposes restrictions on oneself by creating attachments to the world and its illusions. In "doing," you detach yourself from the world, becoming egoless and effortless. In Japanese martial arts, the word mushin is used, which means "no mind." It refers to being void of thought, without emotion, without expectations or anticipation. The idea is to "not think" and let your body do what it has been trained to do, allowing for an uncluttered mind and a quicker reaction time. According to Buddhism, one must avoid the illusion of reality and accept impermanence. By emptying the mind and realizing impermanence, the unification between thought and action can be achieved. This intuition allows an individual to fight effectively, without hesitation. But its true power lies in that it can alert an individual to danger before it strikes, thus making it possible to avoid peril.
According to Gichin Funakoshi, one must expand upon this concept of emptying the mind as it also refers to the emptying of harmful intentions as well. This requires a spirit of humility. It is for these reasons that Gichin Funakoshi changed the character of kara in the word karate, from the meaning of "China" to the meaning of "empty." So the translation of karate to mean "empty hand" implies not only a lack of weapons but an emptying of the mind as well.