secret techniques (of an art or skill); inner mysteries; essence; quintessence; heart
師匠から剣術の奥義を伝授された。
He was taught the secret techniques of swordsmanship by his master.
茶道の奥義を極めるには年月がかかる。
Mastering the inner mysteries of tea ceremony takes years.
奥義を会得した者は少ない。
Few have mastered the secret arts.