The proverb is: 大隠は市に隠る Tai-in wa ichi ni kakru "A great sage lives in a town" Though a hermit may lead a pious life in a cave, in a forest or a lonely mountain, a trully great person, lives in crowded streets and is not affected by his surroundings. He can have a disciplined life in spite of his surroundings. from the book: Japanese Proverbs and Sayings.
Yamada Sensei lives and teaches aikido in the very heart of Manhattan (NYC). Here are Yamada Sensei's words concerning the very same idea:
"I am not a very spiritual man. I should have followed the lectures of Nakamura sensei, I would probably be deeper. I am not a mysterious person, I try to practice and transmit something that is good for the body and the mind, but something rooted in everyday, real life. Zen meditation is good. It can be performed in the depths of the mountains, where nothing disturbs us, but the best place to meditate is in a busy street, this is where you need it. One day, I was in a temple and during a discussion, I told them that it was easy to meditate when one was alone in the world, but that it was a different story when at the heart of a busy street in New York. People got angry but it is in this type of place that relaxation and detachment are needed most (laughs). Always anchor things in reality so that it positively affects daily lives."
The full interview can be found here:
By Ze'ev Erlich