Carl Gustav Jung was a Swiss psychiatrist, and founder of analytical psychology. Jung met Sigmund Freud in 1907, and became the first president of the International Psychoanalytic Association when it was formed. He broke with Freud in 1912, when Jung published his revolutionary Psychology of the Unconscious, which postulated two dimensions of the unconscious -- the personal (repressed or forgotten content of an individual’s mental and material life), and what he termed the collective unconscious (those acts and mental patterns shared either by members of a culture or universally by all human beings). Under certain conditions these manifest themselves as archetypes -- images, patterns, and symbols that are often seen in dreams or fantasies and that appear as themes in mythology, religion, and fairy tales. In Psychological Types (1921) Jung elucidated extroversion and introversion. He held the most significant task for any person to be the achievement of harmony between the conscious and the unconscious. The definitive edition of his collected works in English translation was published between 1951 and 1979.