Covers a variety of mental illnesses. Makes the point that the standard diagnostic system may be inaccurate. Believes that bipolar disorder and schizophrenia are not necessarily discrete conditions.
Made the point that there are many psychological models for depression, and believes that mania is some kind of disguised depression and/or a response to it.
Tries to understand delusions and hallucinations psychologically.
Conclusion is inconclusive, may be various things that cause mental illness.