In Zen, a school of Buddhism, one may reach the ultimate "Absolute." Zen meditation teaches one to focus and reach a level of thought that words cannot describe. Zen teaches one to "know thyself" and not to limit yourself. Samurai used these beliefs as a tool to drive out fear, unsteadiness, and ultimately, mistakes, things could get them killed.
Confucianism gives Bushido its beliefs in relationships with the human world, their environment, and their family. The Samurai followed Confucianism's stress on the five moral relations: between master and servant, father and son, husband and wife, older and younger brother, and between friend and friend. However, the samurai disagreed strongly with many of the writings of Confucius. They believed that man should not sit and read books or write poems all day, for an intellectual specialist was considered a machine. Instead, the Samurai believed man and the universe were made to be alike in both spirit and ethics.
Shintoism, another Japanese doctrine, gives Bushido its loyalty and patriotism. Shintoism includes ancestorworship, which makes the Imperial family the fountainhead of the whole nation and awards the emperor a god-like reverence. He is the embodiment of Heaven on earth. With such loyalty, the Samurai pledged themselves to the emperor and their daimyo (feudal landlords or higher ranking samurai). Shintoism also provided the backbone for patriotism. Samurai believes the land was not merely there for their needs, that it is the sacred abode of the gods and the spirits of their forefathers. They believed that land should be cared for, protected, and nurtured through intense patriotism.