The journey inside you

In 1921 the Swiss psychiatrist Carl Jung published Psychological Types. He noticed that people do not differ only in what they think, but in how their mind works. He described two ways to take in the world, sensing and intuition, and two ways to decide, thinking and feeling. Each can face outward, to people and things, or inward, to the self. Four ways, two directions: the eight functions.

Jung also gave us the words this book is built on: the ego, the conscious self; the shadow, what we do not see in ourselves; the anima, the inner figure that leads us toward the unknown; and individuation, the lifelong work of becoming whole.

Jung's book was hard to read. In the United States, Katharine Cook Briggs and her daughter Isabel Briggs Myers spent decades making it practical. During the Second World War, as many women went to work in industry for the first time, they built a questionnaire to help people find work that suited their nature.

They summed up a type in four letters: where your energy goes (E or I), how you take in information (S or N), how you decide (T or F), and how you deal with the outer world (J or P). That gave the 16 types, and the type names known all over the world today.

Four letters say which functions you prefer, not how they work together. In 1983 Harold Grant and his coauthors set out an order of four functions for each type, from the strongest to the weakest, with the direction changing at each step: if the first faces inward, the second faces outward, and so on. This order is the stack, and it is what most people mean today by the cognitive functions.

The Jungian analyst John Beebe went one step further: if we have all eight functions, then the four we do not use well are not gone. They live on in the shadow, and they act. From the 1980s he gave each of the eight places in a type a character, an archetype in Jung's sense: a pattern of behaviour that every human being knows.

In the light, the four functions of the ego: the Hero, the Parent, the Eternal Child and the Anima or Animus. In the shadow, the same four functions facing the other way: the Opposing Personality, the Senex or Witch, the Trickster and the Demon or Daimon.

For the first time, there were words for who we are when we feel attacked, cornered or completely lost: not someone else, but other characters of the same cast.

In 1949 the mythologist Joseph Campbell, himself a reader of Jung, published The Hero with a Thousand Faces. Comparing the myths of the whole world, he found one story told again and again: a hero leaves the familiar world, crosses into the unknown, faces trials and a great ordeal, and comes back changed, with a gift for others. He called it the hero's journey.

Campbell saw these myths as more than entertainment. They are pictures of a path that exists inside each of us: the way a person grows, by leaving what they know.

Put Beebe and Campbell side by side and the characters of a type start to tell Campbell's story.

Your life starts in the world of your Hero, your first function, the strength you trust. Sooner or later life brings a problem the Hero cannot solve. The call comes from the other end of your spine: your Inferior, your fourth function, the place of your fears and of your deepest longing.

To answer it, you have to cross into the shadow, meet the characters who guard it, and face the Demon, your eighth function, the part of you that you fear most. The reward is the Daimon: the same force, turned into a gift. You come back whole, and what you bring back is for others.

This is the idea behind the whole book: your type is not a box. It is a story that is still being written, and the plot always leads you toward the rest of yourself.

The full mapping of Campbell's stages to the eight seats is in The hero's journey within.

In any order. If you are new to all this, start with the eight functions and how four letters give eight functions. If you know your type, open its chapter. If you came for the story, go to the hero's journey within.

Each idea says who it comes from. Many authors have built on Jung, and they do not always agree; the labels show what belongs to whom, and the Sources page lists their books.