The Impossibility of Knowing is a book that assembles and integrates Jackie Gerrard's clinical work and thinking over the many years of her working life. The chapters in Part I focus on patients with specific types of psychopathology and explore particular difficulties in technique and thinking. There are numerous clinical examples from her practice. Above all, she stresses throughout the book the importance of the enquiring mind and the struggle not to 'know' but to be ever ready to 'not know' and to explore--reflected in the title of Chapter 2--'On Travelling Hopefully'. The subsequent three chapters in part II of the book address the issues of love, hate and the erotic and offer many clinical vignettes of the complexities and sensitivities of work in the arena of passion and sexuality. Erotic transference and counter-transference are vital areas of exploration in psychoanalytic work and technique. Finally, in part III, specific challenges to the psychotherapeutic frame are illustrated in chapters on enactments and on work with an absent patient. The last chapter is written on a lighter note, illustrating some everyday dilemmas that have occurred in the course of her clinical work. The book should be of interest to qualified practitioners, to those who are training in psychodynamic or psychoanalytic work, and to anyone who has an interest in psychoanalysis and the "impossibility of knowing."