"There are many things in martial arts that accord with Buddhism and correspond to Zen. In particular, there is repudiation of attachment and avoidance of lingering on anything. This is the most urgent point. Not lingering is considered quintessential." (Mushashi 1993) This is the intellectual equivalent of "do what comes natural". In Buddhism you eliminate desire because it causes suffering. In Zen Buddhism, you eliminate your attachment to desire because that is what causes your suffering. The difference is that in Zen, desire may be a natural thing as long you don’t linger. Lingering with the sword in Bushido may cause your downfall. Confucianism also had influences on Bushido. It is well known that, if one follows Confucianism, they set a standard of ethics in their daily lives. One of the major influences of Confucianism on Bushido is the concept of "filial piety". Shintoism also offered this influence to Bushido (Nitobe 1908). This concept of "filial piety" corresponds to the Bushido Codes’ necessity of duty and devoutness. One must complete their duties with honor even to the point of death. http://www.japanesebushido.org/