Physical diagnosis was the determination of disease by an external examination of the body. It relied on careful attention to observation, and Hippocrates constantly advised Greek doctors to observe their patients meticulously. The concept of prognosis was also developed by Hippocrates, through which a doctor could predict the course and outcome of a disease based on previous observation of similar cases. The ability to make a prognosis had an important function in society. By predicting the future of a disease process, doctors gained the trust of their patients and were elevated in status above traditional methods.