All of Koons's best art - the encased vacuum cleaners, the stainless-steel Rabbit (the late-twentieth century's signature work of Simulationist sculpture), the amazing gleaming Balloon Dog, and the cast-iron re-creation of a Civil War mortar exhibited last month at the Armory - has simultaneously flaunted extreme realism, idealism, and fantasy.

Imagine it's 1981. You're an artist, in love with art, smitten with art history. You're also a woman, with almost no mentors to look to; art history just isn't that into you. Any woman approaching art history in the early eighties was attempting to enter an almost foreign country, a restricted and exclusionary domain that spoke a private language.

When museums are built these days, architects, directors, and trustees seem most concerned about social space: places to have parties, eat dinner, wine-and-dine donors. Sure, these are important these days - museums have to bring in money - but they gobble up space and push the art itself far away from the entrance.

Billions of photos are shot every year, and about the toughest thing a photographer can do is invent an original, deeply personal, instantly recognizable visual style. In the early nineties, Wolfgang Tillmans did just that, transforming himself into a new kind of artist-photographer of modern life.

A metaphysical tour de force of untethered meaning and involuting interlocking contrapuntal rhythms, 'The Clock' is more than a movie or even a work of art. It is so strange and other-ish that it becomes a stream-of-consciousness algorithm unto itself - something almost inhuman.

I think that a lot of artists have succeeded in making what I might call "curator's art." Everybody's being accepted, and I always want to say, "Really? That's what you've come for? To make art that looks a lot like somebody else's art?" If I am thinking of somebody else's art in front of your art, that's a problem.

Poor Georgia O'Keeffe. Death didn't soften the opinions of the art world toward her paintings.