"The entry for kokoro in a dictionary of classic Japanese words communicates similar notions:
Originally, kokoro referred to the beat of the heart, which was considered to be the essential organ of life and the source of all activities. By extension, kokoro refers to all human activities affecting the outside world through intention, emotion, and intellect.
Kokoro, then, has three basic meanings: the heart and its functions; mind and its functions; and center, or essence."
Kokoro, Defined by Shohaku Okumura