What is the fine line between genius and insanity?

Genius produces something beautiful or something useful. Insanity produces neither.

How can one tell one from the other? (not challenging your opinion, just asking for the sake of discussion)
Isn’t it possible for something to be percieved as useless, but end up having a critical effect on something later?

one person can see an item as insane, but another person can see the same item as pure genius.

Beethoven vs. Charles Manson?
Wagner vs Wagner?

Picasso vs. Nero?

Perception and empathy.

RAMesesII: this is why genius is sometimes mistaken for insanity, but only fools mistake insanity for genius.

cwilbur: Well said.
So, what would be the correct classifications for…
Neitzche?
Hannibal? (the Punic Wars one)
Hitler?
Marx?
Einstein?
Franz Liszt?
Debussy?
Van Goh?
Dali?

Did any of them produce anything useful or beautiful? You wanted a rubric, and I gave you one; apply it as you see fit.

is humbled by cwilbur’s wisdom

Ah… I see. :-)

Kevbo. One look at his avatar and you’ll see what I mean.

The thin line is an optical illusion… Everyone sees it a little differently, and you can’t always tell if it’s there at all…

Mozart and Howard Hughes until they cracked.

ray charles shooting dope in the dark blind.

when what you initially started doing begins to hurt yourself or others. Its not healthy to obsess that much. A good example could be nirvana and pearl jam. Nirvana clearly more genius, but pearl jam can look back and say who was the crazy one.