Kokoro in its simplest understanding is the heart of the warrior. It is the mind, spirit, will, feeling, intention, thought, the character, or core of the warrior. What this philosphy emphasized was a cultivation of the mind because in the words of Yamaoka Tesshu, “If your mind is not projected into your hands, even ten thousand techniques will be useless.” So essentially, without discipline of the mind and heart, which kokoro stresses, one's techniques are useless.
