If ever there was a man to certify the claim” genius by possession.”
That man was the late surrealism/metaphysical painter Giorgio De Chirico.
For about 15 years, roughly 1910-1925, a number of his paintings are among the most
Brilliant, lyrical and mysterious of inspired masterpieces.  After that his work
Astoundingly bad.
It is clear upon reflecting upon his latter work that, although it accounts for something it is not just a question of De Chirico Abandon the metaphysical style.  Picasso painted in many styles and produced shit and masterpieces in all styles, although I would argue
He produced far more masterworks in the cubist era.   Perhaps the clue we gather from the comparison is that an artist is forced to greater creativity when bound by restrictions,
Such as Picasso was restricted w/in cubism and De Chirico was w/in the metaphysical style.  I think its true.  But it is not enough to answer, why does a painter that paints such
Inspired great paintings in one style for 15 years, suddenly change styles and paint some of the most uninspired, unfelt, and generally empty of all feeling and what are not even good paintings?
De Chirco spoke of his recovery from a sickness and the strange mood he had felt
Shortly before beginning the metaphysical paintings.  The architecture and the things
About him, gave him such a feeling of unease that he set out to capture the feeling.
His words describing the feeling are reminiscent of the beginning chapters of nausea.
Obviously this was not a simple matter of an artist trying to paint a remembered mood,
For one thing a memory usually loses some of its intensity long before 15 years.
The genius of these painting and the enormous difference in the quality of his latter work,
Suggests that DE Chirco was possessed by some form of genius.   I shall not try to describe
His best work for it is foolish to do so; it is like describing anything that has the brilliant
Hand of genius that gives things a feeling of inevitability
My assumption is, that De Chirico did not merely change styles or tire of the metaphysical
Painting, but that the muse of genius had left him.  That is a pretty romantic view, so here
Is another way of saying the same thing.  The genius or sickness (it is not just a romantic fable, although, they overstated to mythic status, the coexistence of madness and genius)
That which gave him an open window into these feelings, had snapped shut.  He was no longer capable of tuning into the feeling, and without the feeling that was guiding him, De Chirico had two options.  One, he could plodder on and hope the feeling came back, in
Which case he would be left to make uninspired metaphysical paintings.  Two, he could
Try a new style.  When an intense feeling is no longer present it would seem that trying something new would be refreshing to one waking up from possession, much like waking up from mad love.   The problem for De Chirco was not that he went to a new style rather than faking it, the problem was that without the intense feeling to guide and restrict him from going off the path was gone.   Now he was hostage to his own vices and ego as a painter, freed from the discipline of staying true to experience and intense feeling, De Chirco was free to make the worst sort of unfelt painting known
He made many ridiculous remarks latter because all sorts of folks hated his latter work.  He saw it as part of an art world conspiracy.  He rightly saw the manipulation of the art market and other disreputable practices but he didn’t see that eventually his latter work too would have its share of revisionist chic writers championing it.  And he didn’t see that
It was not a case of conspiracy, but that his work was horrible!  In what the other surrealists (and if there ever was a bunch of contradictory and venomous bunch, it was the group lead by Brenton) considered his gravest betrayal was that for years after, while making his bad paintings, De Chirco was also doing fakes and copies of his old work and post dating the paintings!
Genius came and went for De Chirco.  Perhaps had he been willing to pay the price, it could have come again.  But even without genius great paintings can be painted.  In fact
The number of masterpieces by even the greatest painters are far out weighed by the number of good, great, average, or even bad works they painted.  It seems that without
The hand of inspiration and the demands of possession guiding him, De Chirco reverted
To a very average painter with no genius to restrain him, but a huge ego that thought
He was a genius.  A bad combination that, for without inspiration or understanding his own limitations as a painter De Chirco was set loose to accomplish the sort of bad painting that can only be achieved by one with just enough talent and no feeling and a huge ego could possibly achieve.