It is easy to crush an enemy outside oneself but impossible to defeat an enemy within. 

Eiji Yoshikawa

Japanese novelist Eiji Yoshikawa (born August 11, 1892) is best known for his historical work Musashi, a vivid account of the life of a samurai. The author’s real name was Yoshikawa Hidetsugu, and primary school was the extent of his formal education. But he went on to write more books on Japanese historical figures, and he won major awards and was highly regarded for his literary achievements, historical knowledge, and psychological insight.