It is unlikely that Carl Jung would approve of the MBTI (Myers-Briggs Type Indicator) personality test and its use in modern society. Jung warned that using his theory for better self-understanding is not that simple, and he repeatedly objected to the popular interpretation of his book Psychological Types and research based on the MBTI instrument. There was a rift between Isabel Briggs Myers and Carl Jung, which has been hidden for more than half a century from those who use Myers-Briggs typology. Although the MBTI is based on Jungian psychological types, there are some important differences between Jung's theory and the MBTI. Therefore, it is questionable whether the MBTI accurately reflects Jung's ideas about personality types.