Diagnosis (διάγνωσις, Lat. cognitio), lit. ‘the means of distinguishing, or recognizing’. The concept of diagnosis is important in ancient forensic oratory and law, but the most extended accounts of its importance are found in the medical writers. Much ancient medical literature is concerned with the way in which the doctor should discern the nature, history, and future course of the patient's illness. Each case dealt with by the doctor involved the recognition of a number of signs which needed to be distinguished and ordered so that the correct treatment could be prescribed, and the progress of the disease anticipated. Prognosis (πρόγνωσις) is effectively a part of diagnosis, and many ancient diagnoses result not so much in naming the affection as in predicting its outcome. Effective prognosis not only increased the patient's confidence in the doctor, but could also encourage the doctor to avoid hopeless cases.A group of Hippocratic treatises, including Prognostic, Prorrhetic, and Critical Days, deal with the nature of the signs presented to the doctor by the patient.