In some cases, eccentricity spilled over into mental instability: Paul Ehrenfest's desire to keep up with developments in quantum mechanics eventually drove him to suicide.

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Generally, those reasonable regulations would be about criminal background, background of mental instability, basically the ones that are outlined in the opinion of the judge who wrote the Parker decision, Judge Silverman.

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She told him (and the rabbits that sometimes surreptitiously accompanied the riders) that people were becoming more and more unbalanced: studies had proved it, which led the psychiatrist to conjecture that perhaps mental instability was not so much a disease as a stratum of normality, just below the surface of normality as it was commonly conceived.

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Today it is widely perceived as a medical problem, almost exclusively the result of mental or emotional instability.

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Many people fail to recognize legitimate reasons for homelessness, such as domestic abuse, economic instability, and mental illness.

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Bipolar disorder is a mental disorder that presents with recurrent episodes of mood instability of feeling 'high' (mania or hypomania) and 'low' (depression).

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