Hippocrates says, "It appears to me a most excellent thing for the physician to cultivate Prognosis..." This book is about his understanding of prognosis.

Prognosis is an epidemiological term defined as the relative probabilities of the various outcomes of the natural history of a disease and can be made about any outcome of an illness. It seems to be highly desirable that a physician should pay much attention to prognosis. If he is able to tell his patients when he visits them not only about their past and present symptoms, but also tell them what is going to happen, as well as to fill in the details they have omitted, he will increase his reputation as a medical practitioner and people will have no qualms in putting themselves under his care.

Hippocrates (c. 460 – c. 370 BC), was a Greek physician of the Age of Pericles (Classical Greece), and is considered one of the most outstanding figures in the history of medicine. He is referred to as the father of western medicine in recognition of his lasting contributions to the field as the founder of the Hippocratic School of Medicine. Hippocrates is commonly portrayed as the paragon of the ancient physician, credited with coining the Hippocratic Oath, still relevant and in use today. He is also credited with greatly advancing the systematic study of clinical medicine, summing up the medical knowledge of previous schools, and prescribing practices for physicians through the Hippocratic Corpus and other works.