I have been mulling-over the idea that genius could be regarded as a form of power; when power is considered as being able to shape the world according to desire.
This captures the ambiguity, or two-faced quality of genius - that because it is power, it can be used for good or ill.
By this account there used to be large numbers of individuals who were gifted with exceptional power; and if this was combined with hard work and luck, these individuals each had an exceptionally large influence on the world.
The 'world' that genius influences necessarily includes the human world, and may be restricted to the human world. So genius in the arts is of this type.
But let us first consider scientific, technical, economic genius - the kind of genius which when found in high concentration for several generations led to modernity: this world of increasing productivity, capability, specialization.
A scientific genius re-orders some aspect of the world - by discovery, invention, theory - and this re-ordering survives, spreads, replicates through the human world.
It is as if the genius is the origin of an epidemic, or the first of a successful lineage of mutants.
But this is purposive, it is non-random - the genius knows what he is doing, and knows what he is trying to do - even if he cannot possibly predict the consequences of succeeding.
And this is where the transcendental aspect of genius comes in. There are those who are gifted with the potentiality for changing the world, and they, as individuals, have a choice - a profound choice - how they deploy that gift, in which direction they point that gift.
As the gift unfurls itself, they will be confronted with forks in the road when they are able to choose and to influence the direction of the power they are unleashing - and whether it will be for God, or against God.
The way that it works is that the whole nature of the power unleashed may be decided by this quantitatively small choices - so that, in effect, a genius may create a power that is 99.9 percent Good; yet is evil in nature due to one choice made.
In Tolkien's world, Feanor is the greatest ever genius of science, and is defined by the unsurpassed beauty of the Silmaril jewels - yet his choice not to allow the jewels to be sacrificed in order to restore the light of the destroyed trees of light, is an evil choice which sets in motion a vast tide of misery and further destruction.
The Silmarils are thus almost wholly good - yet from this choice, and from the possessiveness they engender - are a net evil.
This is a symbol of genius. There are - or were - individuals with Feanor-like power to change the world; but the cumulative misdirection of this power, generation upon generation, has led to the psychotic, purposively evil aspects of the world which are ascendant.
This has been the doing of genius in the world of the arts, just as has the several generations of rapid economic growth, the several centuries of increasing scientific and technical capability...
So many of the geniuses of the past chose, in the crux, to deploy their power against God: sometimes very obviously and explicitly, sometimes (as with so many of the scientists) simply by leaving-out God or by eroding his nature.
I found the seeds of this idea in George Orwell's essay on Salvador Dali - where Orwell acknowledges that Dali was, qua painter, of genius or near-genius level - but deployed this power to sicken and demotivate, to poison the minds of many. At a lesser level, something similar is true of painters such as Francis Bacon and Lucien Freud.
And the same could be said of many or most artistic geniuses in the past century especially - and although some repented, they were not able to undo the harm done by the unleashing of evil-directed power in their early work.
So, James Joyce was an unrepentant genius who unleashed his amazing power over language against God; and TS Eliot did the same in works such as Prufrock and The Waste Land - which have acted like a residual toxin on the world view of four generations.
Eliot's later repentance seems incomplete (since he seems not to have repudiated the early work which made his name) - but either way the harm had been done: the toxic phrases had been launched on the world, had replicated, had become an epidemic.
In science and technics, a similar phenomenon has of course been at work.
Geniuses have, by and large, lined-up to attack God and tradition - and the changes they wrought have not, therefore, taken life and then enhanced it by addition of Good and subtraction of evils; but have instead utterly transformed life;
such that people have become so deeply perplexed they cannot make comparisons nor evaluations - but simply gaze around bewildered as they are swept out into the ocean by a tidal flow which they cannot comprehend; the withdrawing tide of faith generated by cumulative individual choices of past genius.