Emil Kraepelin (born 15 February 1856 - 7 October 1926) German psychiatrist. In 1883, he said that brain pathology causes mental illness. Kraepelin has classified and defined behavioral disorders for the first time. During this period, supernatural beliefs were completely abandoned (though not among the public), and physicians accepted the relevance of many mental illnesses to brain pathology. For the first time mental illnesses were recognized as illnesses with Kraepelin, just like somatic illnesses. Researches investigating brain pathology have been conducted using anatomy, physiology and biology. German philosopher and psychiatrist who deals with the limits of various sciences in their attempts to explain the world and the human. Inspired by Kant and Kierkegaard, he tried to draw the path that transmits human existence to greatness, with the philosophical system that opposes Nazism.