A core concept in modern psychiatry since DSM-III was released in 1980, is the categorical separation of mood disorders from schizophrenia, known as the Kraepelinian dichotomy. Emil Kraepelin introduced the idea that schizophrenia was separate from mood disorders after observing patients with symptoms of psychosis and mood disorder, over a century ago, in 1898. This was a time before genetics were known and before any treatments existed for mental illness. The Kraepelinian dichotomy wasn't used for DSM-I and DSM-II because both manuals were influenced by the dominant psychodynamic psychiatry of the time, but the designers of DSM-III wanted to use more scientific and biological definitions. Consequently, they looked to psychiatry's history and decided to use the Kraepelinian dichotomy as a foundation for the classification system.