Diagnosis

Diagnosis (Gr., from dia, 'through,' and gnōsis, 'knowledge'), in Medicine, the discrimination of diseases. It includes the study of all the vital phenomena of diseases, and also of their appearances after death, in so far as this can aid their discovery during the life of the patient. It is usual to speak of rational or physiological diagnosis, or diagnosis by symptoms—i.e. changes chiefly functional, observed by the patient; and of physical diagnosis, or diagnosis by signs—i.e. objective phenomena appreciable by the senses of the observer. The latter method of diagnosis has been much enlarged in scope and increased in importance by the modern methods in medicine of Auscultation (q.v.) and Percussion (q.v.), and also by the great advances made in physiological chemistry, and by the use of the microscope. Skill in diagnosis is one of the highest gifts of the physician, and nothing distinguishes the man of long experience from the tyro more than this unerring insight into some unseen disease. See STETHOSCOPE, LARYNGOSCOPE, OPHTHALMOSCOPE, &c.