It's been said there's a 'thin line' between genius and insanity.
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This has been proven to be a myth if you measure genius by traditional IQ. However there certainly are many kinds of intelligence or genius that would not be measured on those scales. I read the research that shows no correlation between very high IQ and psychiatric disorders when I did my masters Degree in Education of the Gifted and Talented. Ther is so much variation in what one considers "genius" I think it's very hard to isolate just a few indicators. Someone could have a very high IQ but a poor memory for details and facts. Someone else might have just an above average IQ but a great memory which would impress many people. I tend to see genius as someone who is smart but also inventive. Sometimes genius manifests as result of a passion and talent for just one discipline, yet other times the person is more of a "big-picture" thinker and sees connections between apparently disparate disciplines.
I love this quote : "Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it." (Alan Perlis, Epigrams in Programming.) yet here i am trying to be an astrologer which is a discipline of intense complexity!
I have seen that Jupiter conjunct or in aspect to Uranus gives significant gifts and talents and in air or fire or cadent houses would often manifest as intellectual talents. Mercury added to the complex by aspect would enhance it. I knew someone with that conjunction in Cancer on his ASC and he is a amazing, talented salesperson. Mercury well aspected by more than one outer planet . Galilleo's mercury is in tight aspect to almost everything in his chart.
But i have seen a great variety in charts of really smart and talented people.
Musical talent shows up usually with Jupiter in flowing aspect to the Moon. Mozart has Moon conj. Pluto sextile Jupiter