Why is the Georgia O'Keeffe Museum selling her work?

What struck me about the Georgia O'Keeffe sale was not the high price paid for the work.

Nor was it the discrepancy between what the market will pay for art made by men and what it will pay for art made by women, the reasons for which have never been entirely clear.

Is it ingrained sexism, or, as Germaine Greer told me in her opinion, historically work by female artists has generally not been as good as that produced by their male counterparts?

No, what caught my eye was the institution selling the painting, which was The Georgia O'Keeffe Museum. Doesn't that strike you as odd? A museum selling an artwork by the artist it was founded to represent?

I can't imagine it happening in this country, where our museum collections are like Venus flytraps: once an artwork goes into the collection, it ain't ever coming out (unless there are truly exceptional circumstances).

The Americans take a more strategic approach when it comes to buying and selling work in and out of institutional collections. They generally have a policy of "trading up", whereby lesser works are sold to raise the necessary money to buy better examples from an artist's oeuvre.

That makes sense. But does it make sense for The Georgia O'Keeffe Museum to sell a painting the market - even at the original estimate of $10-$15m - considered to be of the highest quality?

The current trustees obviously think so, but I wonder if those running the museum in the future will agree?