What would Carl Jung make of 2011?

Carl Gustav Jung died 50 years ago today. Alongside Sigmund Freud, he is arguably one of the two people of the 20th century who most shaped the way we think about who we are. But what would he make of the 21st century so far, asks Mark Vernon.

Have you ever discussed whether you were introverted or extroverted? Undergone a personality test on a training course? Wondered what lurks in the shadow side of your character? Carl Jung is the person to thank.

The Swiss psychologist devised a series of personality types. He coined introvert for someone who needs quality time on their own and extrovert (although Jung spelled it "extravert") for the person who never feels better than when in a crowd. Personality tests, such as Myers-Briggs Type Indicators, draw directly from them.

The shadow side of your character is that part of you which is normally hidden, but sometimes leaps out, catching you unawares. Why is it that the calmest people curse and swear when driving in traffic? Why is it that upright citizens sometimes commit crimes of passion? Jung had an answer - we all carry a shadow....