The notion of "religious experience" can be traced back to William James. He used the term "religious experience" in his book, "The Varieties of Religious Experience". It is considered to be the classic work in the field. At professional conferences, people often cite this book. James makes a difference between institutional religion and personal religion. Institutional religion refers to the religious group or organization, and plays an important part in a society's culture. Personal religion, in which the individual has mystical experience, can be experienced regardless of the culture.