The word ki is very often used in the daily conversation of Japanese people, and it is thought of as a welder of Japanese interpersonal relations. Here ki has been investigated from several angles, such as etymology, semantic and phonetic derivatives, ki as personality-trait names, and idiomatic phrases using the word ki. As a common object of participation mystique of two persons in psychotherapy, ki influences them, sometimes alien to ego-consciousness and sometimes identified with it. Indeed ki is nothing more than a concept, a word we manipulate in everyday life, but all the more so we are unconscious of its influential power over us. As one etymology of a Japanese term "to listen to" is "to receive ki ", the art of listening requires an appreciation of how the dynamics of ki affect the two people involved.