From [1941] onward, [Patricia Highsmith] essentially maintained a double account of her life: whereas she used the diary to detail her intense, at times painful personal experiences, she used the notebook to process these experiences intellectually and muse on her writing. Pat’s notebooks were workbooks, and a playground for her imagination. They contain style exercises, insights into art, writing, and painting, and what Pat liked to call Keime (a German term meaning “germs”), ideas and whole passages for potential short stories and novels. Her diaries help us better understand the notebooks; they arrange the notebook entries within what seems to be a truthful time frame and personal context. Diary and notebook entries are interwoven and interlocked, the diary entries dated in long form (month, day, year), the notebook entries in numerical form (with slashes), as was Pat’s style. While the two formats can be read independently of each other, when read in tandem they help to gain a holistic understanding—in Pat’s own words—of an author who concealed the personal sources of her material for her entire life, and whose novels are more likely to distract us from who she was, than lead us to her.

Anna von Planta, in Patricia Highsmith: Her Diaries and Notebooks: 1941–1995, edited by Anna von Planta