Although it stands to reason that a samurai should be mindful of the Way of the Samurai, it would seem that we are all negligent. Consequently, if someone were to ask, "What is the true meaning of the Way of the Samurai?" the person who would be able to answer promptly is rare. This is because it has not been established in one's mind beforehand. From this, one's unmindfulness of the Way can be known. Negligence is an extreme thing.
Excerpt from the 1st Chapter of Hagakure

Hagakure, meaning “In the Shadow of Leaves”, or Hagakure Kikigaki, is a practical and spiritual guide for a warrior, drawn from a collection of commentaries by the samurai, Yamamoto Tsunetomo, former retainer to Nabeshima Mitsushige, the third ruler of what is now the Saga prefecture in Japan. Tsuramoto Tashiro compiled these commentaries from his conversations with Tsunetomo from 1709 to 1716; however, it was not published until many years afterwards. Hagakure is also known as the The Book of the Samurai, Analects of Nabeshima or the Hagakure Analects.

After his master died, Tsunetomo himself was forbidden to perform Tsuifuku, a retainer’s ritual suicide, by an edict of the Tokugawa Shogunate. Hagakure may have been written partially in an effort to outline the role of the samurai in a more peaceful society. Several sections refer to the “old days”, and imply a dangerous weakening of the samurai class since that time.

The book records Tsunetomo’s views on bushido, the warrior code of the samurai. Hagakure is sometimes said to assert that bushido is really the “Way of Dying” or living as though one was already dead, and that a samurai retainer must be willing to die at any moment in order to be true to his lord. This is a misreading of the statement “The way of the samurai is found in death”, which was intended to mean that a samurai must always think of his death in order to do things well.

Hagakure was not widely known during the decades following Tsunetomo’s death. However, it received wider circulation at the start of the 20th century, and by the 1930s had become one of the most famous representations of bushido thought in Japan. Hagakure remains popular among many non-Japanese who are interested in samurai culture. It is also frequently referred to as The Book of the Samurai and was featured prominently in the 1999 Jim Jarmusch film Ghost Dog: The Way of the Samurai.