This article aims to analyse, based on dream interpretation, the transformation in the psychotherapeutic process. The selected dreams illustrate transformative thinking according to Bion’s theory, which ultimately serves to achieve the required separation and individuation. The initial material, subjected to psychotherapeutic treatment, came from three sources defined as: i/ introspective (memories), ii/ dreamed (daydreams) and iii/ fantasised (waking dreams). Eight of the patient’s dreams, dreamt between session one and session fifty, during the two years of psychotherapeutic work (involving a total of 102 sessions), became the principal subject of therapeutic analysis. The descriptions of the dreams were written by the patient herself when the therapy process had been completed, based on the transcriptions of the sessions. The comments from the psychotherapist have been made analogously from the transcript material. By using a unique method — a parallel, independent description of: 1/ the patient’s relevant experiences together with her understanding of them from her perspective, and 2/ the analysis of the psychic material (memories, daydreams, etc.) made by the psychotherapist’s perspective, it became possible to trace part of a complex transformative process. The understanding and presentation of the complex task of seeking the truth, the most important effect of transformative thinking, has been rooted in Bion’s concept and Jung’s theory. It is an attempt to answer an important and intriguing question: what is the significance of the activity of dreaming in transforming the patient’s experience, leading her to psychological maturity – individuation?