Here are some speculative remarks to illustrate the development of my thinking about genius:
Genius is the high end of the dimension of creativity.
Creativity in turn is the outward expression (effect, result, projection) of awareness. Awareness is what the creative individual experiences inside one's mind ("the experience of experience itself", as I have called it before; the being aware of the fact that one or anything exists), while creativity is what others perceive when observing that individual. Awareness and creativity are the inner and outer aspects of the same thing. One's creativity is a measure of one's awareness. A non-creative person is not aware; A genius is the most aware of all.
Awareness is related to creativity not just as in making a painting or writing a novel, but also as in my philosophical hypothesis "Only what can be verified by aware beings exists". Awareness is thus responsible for the creation of existence itself. Without aware beings, nothing would exist.
The components of creativity (and therefore of awareness and of genius) are intelligence, conscientiousness and associative horizon.
Conscientiousness is the only aspect of creativity that can be improved significantly, permanently, safely and purposely in an adult. This is probably so because conscientiousness is not a unitary trait, but comprises various traits, some of which are independent, and not per se correlated with each of the other traits that make up conscientiousness. Conscientiousness is a kaleidoscope of good features, and it is possible to possess different combinations thereof, and to gain or lose some of them without affecting the rest.
Associative horizon can probably not be safely improved much; Hallucinogenic drugs widen it, but at the great risk of psychosis, which causes permanent damage to the mind and brain. Perhaps studying the work of geniuses or doing exercises in "lateral thinking" may improve one's associative horizon a bit, but one must ask if the result is worth the effort, and realize that much more creativity can be gained by improving conscientiousness. Associative horizon is the "spark", it is Edison's "2% inspiration", as opposed to the "98% transpiration". There is a tendency among people fascinated by genius to focus on the 2% and neglect the 98%, the hard work that comes after the "spark". A tendency to confuse creativity with associative horizon. This is the phenomenon of "wanting a champagne taste on a beer budget"; The attraction of being creative in a flash of insight, without needing to do the hard work.
There is a critical tension between the three components of creativity; each, when exceeding a certain threshold, can bring down the whole, destroying creativity.
Associative horizon, when exceeding a threshold, leads to psychosis and thus destroys creativity. This has been pointed out by Hans Eysenck and others. For genius, one needs to be close to that threshold.
Conscientiousness, when exceeding a threshold, leads to obsessions and compulsions (which in turn cause anxiety and depression) and thus destroys creativity (through neurosis rather than psychosis), be it less drastically. This is part of regular psychiatric knowledge. For genius, one needs to be close to that threshold.
Intelligence, when reaching the very highest altitudes, somehow reduces the frequency of genius; It has been pointed out that geniuses tend to have high, but not the highest intelligence; that those with the very highest I.Q.s are typically not geniuses. I do not know the precise mechanism yet, but relevant is my own finding that, in the high range, there is a significant negative correlation between I.Q. and 1) psychiatric disorders in oneself; 2) psychiatric disorders in one's parents and siblings (which reflect genetic disposition); 3) disposition for psychiatric disorders as measured by personality tests.
Perhaps the very highest I.Q.s tend to go with just a bit less than the needed extreme conscientiousness and associative horizon (both of which are forms of disposition for psychiatric disorders)? Perhaps those with the very highest I.Q.s are too neurologically "normal"?
This possible limiting effect of the very highest I.Q. levels is something I am not certain of yet, but the other two thresholds seem to be real.
In short, my current view on creativity (and therefore genius) could be expressed as:
I have tried to express in a mathematical model how the three aspects work together to produce creativity, but to date have no satisfactory version of such. What I do suspect now is that the amounts of conscientiousness and associative horizon required vary with intelligence; that higher intelligence levels need, and can tolerate, higher amounts of the other two aspects to result in creativity.
I imagine that for each intelligence level there is a certain minimum and and a certain maximum amount of conscientiousness, and a certain minimum and and a certain maximum amount of associative horizon, above and below which there is no creativity. Both of the aspects have to be within these limits, and there may be a single optimum between those limits that is required for genius. The limits and optimum as it were shift upward with intelligence, are relative to intelligence.
Recently I have become somewhat pessimistic about the possibility of expressing associative horizon and conscientiousness each on a scale similar to intelligence and combining them mathematically to obtain a measure of creativity. Instead I have been thinking of combining the three aspects at or under the level of test items, so that the test's raw score will directly reflect creativity. This was actually what I attempted with some of my very first tests, but I concluded later that those tests were measuring mainly intelligence and probably not to a great extent creativity. It may be a future challenge to design problems or tasks that truly require creativity as I define it. Meanwhile, the report Your profile based on Cooijmans tests may help to get insight into one's profile over components of creativity.