**1. Introduction**

In 1844, Soren Kierkegaard [1] wrote of anxiety as being the 'dizziness of freedom', the dizzying effect of looking into the boundlessness of one's own possibilities. Without anxiety there would be no possibility and therefore no capacity to grow and develop as a human being.

This chapter will examine psychoanalytic concepts of anxiety, in particular those of Sigmund Freud and key figures in the British School of Object Relations Melanie Klein and Wilfred Bion. It will demonstrate the close links between psychoanalytic theories on anxiety and the existential thinking about anxiety as espoused by Kierkegaard. The chapter will look at how the role and function of anxiety is an important determinant in the development of symbolic functioning, in creativity and most crucially in the origins of thought and thinking.

Clinical vignettes and material taken from psychoanalytic psychotherapy with children and teenagers will be drawn upon in order to extrapolate thinking about anxiety that is in the service of growth and development (possibility) and the unbounded anxiety which undermines and can arrest personality development, potentially leading to psychopathology.
