As the market has endorsed and enriched him, Koons has swollen, in his two latest series “Antiquity” and “Gazing Ball”, into the most tedious self-imitation. “Balloon Venus” blends his own inflatables lexicon with the archaic forms of the Venus of Willendorf. Outsize plaster replicas of classical figures – “Farnese Hercules”, “Ariadne” – bearing bright balloon-like glass spheres are destined, no more and no less than the garden ornaments they incorporate, for manicured suburban lawns.

“He says, if you’re critical, you’re already out of the game,” announced Koons’s dealer David Zwirner when these repetitive follies launched last year. Dollar power goes some way to explaining why Koons’s smooth sales-speak – “when people make judgments, they close all the possibility around them” – is not seen for what it is: a reversal of the spirit of intellectual openness that has allowed art to flourish since the Enlightenment. And of course it is obvious why Koons, like any entrepreneur boasting a luxury monopoly, directs his factory to produce a controlled stream of high-end, high-tech baubles. Less obvious is why this trading currency for the super-rich should interest the rest of us, or why museums and critics are endorsing it.