Shifting from an emphasis on active and passive modes to the related modes of doing and being alerts us to ways in which patients may think about the therapeutic process, at least at the outset of treatment. While psychoanalysis has evolved in remarkable ways over the last century, free association remains a cornerstone – arguably the cornerstone – of psychoanalytic practice. The term underscores the passive nature of free association – what "occurs" to the patient in the way of "chance thoughts," "spontaneous thoughts," or "unwilled thoughts". The fundamental rule requires the patient to surrender to a more passive mode of experiencing and attending to internal psychic content – letting things "occur" to him without actively picking the topics to be discussed – those he believes constitute the most potentially fruitful subjectmatter to discuss. Certain sorts of patients are particularly challenged by the task of freely associating – in particular, patients whose thinking tends to be obsessional in nature.