Detailed classification and description of mental disorders did not begin in Europe until the late eighteenth century. Psychiatry became a subject for academic study in German universities in the nineteenth century. Kraepelin created the concept of schizophrenia, which he saw in terms of neuropathology. Bleuler, however, saw schizophrenia as a psychological disorder. His ideas became influential in the USA, but Kraepelin's dominated diagnostic habits in Europe. By the 1970s, the need for standardized methods of reaching a diagnosis was recognized. Operational definitions were developed that provided a set of clearly defined criteria but standardized diagnostic procedures do not eliminate the need for skilled and experienced clinicians to conduct psychiatric interviews.