The philosophies of Buddhism and Zen, and to a lesser extent Confucianism and Shinto, influenced the samurai culture. Zen meditation became an important teaching due to it offering a process to calm one's mind. The Buddhist concept of reincarnation and rebirth led samurai to abandon torture and needless killing, while some samurai even gave up violence altogether and became Buddhist monks after realizing how fruitless their killings were. Some were killed as they came to terms with these realizations in the battlefield. The most defining role that Confucianism played in samurai philosophy was to stress the importance of the lord-retainer relationship—the loyalty that a samurai was required to show his lord.