Musashi did not have a master daimyo so he was a ronin.
He had more than 60 sword duels, the highest number recorded. He is said to have killed 17 people in his battles. His first battle was when he was 13.
He was very strong and a skilled carpenter, architect and an artist. He was about 180 cm while an avg. samurai was 150 cm tall.
He is famous for his technique of using two swords in his two hands as usually the katana is held with both hands.
He wrote a book to train the samurais and the swordsmen. The book is recommended to everyone including martial arts practitioners and business leaders.
Miyamoto emphasized that the techniques are less important than the overall goal. The same fighting principles apply to not only one-on-one conflicts but also army battles. The 5 rings represent the five episodes Musashi wrote: The book of earth: martial arts, leadership and the importance of training. The book of water: Swordmanship techniques. The book of fire: the importance of timing. The book of wind: the most common fighting errors. The book of void: strong mindset, mindfulness and zen.
In his book, he stated:
“Do nothing that is of no use”
“If you wish to control others you must first control yourself”
“From one thing, know ten thousand things”
“It is difficult to understand the universe if you only study one planet”
“In battle, if you you make your opponent flinch, you have already won.”
“Do not regret what you have done”
“If you do not control the enemy, the enemy will control you”
“Respect Buddha and the gods without counting on their help”
“The important thing in strategy is not to suppress the enemy’s useful actions but allow his useless actions”
“Perception is strong and sight weak. In strategy it is important to see distant things as if they were close and to take a distanced view of close things.”