If you learn indoor techniques, you will think narrowly and forget the true Way. Thus you will have difficulty in actual encounters.
Miyamoto Musashi, Yamamoto Tsunetomo, Inazo Nitobe (2010). “Honor: Samurai Philosophy of Life - The Essential Samurai Collection; The Book of Five Rings, Hagakure: The Way of the Samurai, Bushido: The Soul of Japan.”, p.14, Bottom of the Hill
