I have to disagree with both of you. This might be wikipedia (http://en.wikipedia.org/wiki/Creativ...mental_illness) but it cites numerous legitimate studies which show a correlation between creativity and mental illness.
Obviously, as you have admitted, citing Wikipedia is questionable. There are indeed several studies suggesting a correlation between mental illness and creative genius... but correlation is not the same as proof of cause. You should also read those studies that offer alternative interpretations of the data. One study that I read not long ago admitted that there was a small but statistically significant increase in mental illness among those employed in creative careers. There were several suggestions explaining this, including:
1. Those employed in areas such as medicine, finance, engineering, business, law, etc... are less likely to report instances of mental illness due to fear of repercussions.
2. Those employed in more creative fields such as art, music, literature, theater, etc... tend to feel more comfortable with the idea of mental illness... and may even be motivated to exaggerate the same as a result of the romantic notions of the "mad artist."
3. Those suffering from mental illness often avoid careers with rigid time frames, deadlines, stressful demands, and requirements that one work well in a group and turn instead to more creative fields where there is greater freedom with regard to scheduling, deadlines, and requirements for working with others.
4. Those diagnosed with mental illnesses and collecting public support or disability payments often turn to the arts as a part-time career or source of income.
The reality is that studies have shown a small correlation between mental illness and creative thinking. There may be links or similarities between the thinking patterns of the mentally ill (or certain aspects of the mentally ill) and the sort of creative leaps in logic or illogical/irrational associations that are found in creative thinking... but this is far from suggesting that creativity is "helped" or "inspired" by mental illness.
Van Gogh is often used as the poster-child for the "crazy artist"... but the reality shows something far more complex. During his manic stages, Van Gogh had endless energy and was able to churn out paintings at a blazing speed. On the other hand, during his periods of depression, he was completely unable to work at all and often needed to be hospitalized. It was during one of his periods slipping from the manic to depression that Van Gogh shot himself.
One might suggest that Van Gogh's illness was a source of inspiration. This may be true... but only in the sense that everything that the artist experiences can be a source of inspiration. Some artists have lived the most tragic lives and turned this tragedy into fuel for their art. Others have lived the most joyful existences... or the most mundane... and turned these into works of art that are just as powerful.
The notion that mental illness is a source of artistic inspiration to the extent that it is a benefit or advantage is nothing more than building upon the naive Romantic notion that art is the result of suffering. We cannot say whether Van Gogh would have been the same artist had he not suffered from mental illness... but it is quite likely he would not have committed suicide and would have had many more years to further develop his art.
We can all cite personal experiences... which add up to nothing. Personally I know a good many working artists... none of whom suffer from mental illness. On the other hand, I have had several individuals in my family who have suffered from mental illness. None of them were the least bit creative. All of them saw their disease as the most horrible curse... two choosing to end it through suicide.
Personally, I hate the attempts to link creativity or the arts with mental illness because I feel it often grossly Romanticizing just how horrible mental illness can be. I also find it a naive, insulting Romantic notion of art and artists... as if all one needs to do is drink heavily, take lots of drugs, engage in antisocial behavior... and be a little "crazy"... and voila! you have a creative genius.
Again... I have seen nothing to convince me that artists are not made up of individuals just as unique... and of just as great a variety of human being as any other walk of life.