This historical essay documents the clinical practices of C. G. Jung and Toni Wolff with their analysand Tina Keller, a Swiss physician and psychotherapist, during the formative years of analytical psychology (1915-1928). The topic is investigated through an examination of primary documents, largely unpublished, in English and German, based on Keller's autobiographical writings. It presents biographical information on Keller's life and details of her analyses with Jung and Wolff, emphasizing the technique of active imagination and describing the clinical practices of Jung and Wolff in Keller's analyses.