Ok jin I know what is Yin Yang. My question was just to know if your teacher explain this in the practice of aikido (or in an other practice).
cguzik: only in kokyu-nage?? Are you sure?
Actually, I was referring to kokyu in the more generic sense, as breath-energy. In this context I would say kokyu is part of all aikido, not just the particular throw we call kokyu-nage. In this way yin and yang are also part of all aikido... the study of giving and receiving.