Whereas modern clinicians are often reluctant to discuss prognosis with their patients, such discussions were central to medical practice in ancient Greece. A historical analysis has the potential to explain the reasons for this difference in prognostic practices and provide insights into overcoming current challenges. Many scholars consider prognosis to be the principal scientific achievement of the Hippocratic tradition. The earliest treatise on the subject, On Prognostics, defines prognosis broadly as "foreseeing and foretelling, by the side of the sick, the present, the past, and the future." This definition makes clear that prognosis is not simply about predicting the future, but also involves an appreciation for the continuity of past, present, and future as sequences of connected events, or trajectories, that can be pieced together into a comprehensive story of the patient's health. In modern medicine, prognosis has lagged behind diagnosis and treatment in its establishment as a central component of medical care. An important basis for understanding this lies in the paradigm change that occurred with the discovery of pathogens as agents of disease, shifting attention toward individual diseases and away from diseased individuals. With this shift, diagnostics and treatments advanced dramatically and prognosis fell to the background. More recent attempts to advance prognosis have focused on narrower uses of the term, such as estimates of life expectancy and mortality risk. However, physicians have expressed a number of reservations about the use of such estimates in the care of patients, and patients have indicated the desire for a wide variety of predictive information. Adopting the broadness of the Hippocratic definition may allow clinicians to overcome their hesitancy and provide much-needed information to their patients.