Contributed by David Carrier / For a long time, I have always thought of Richard Diebenkorn as a great painter. A couple of his paintings were in my local museum, the Carnegie Museum of Art in Pittsburgh, where I treasured seeing them. But he was, so I believed, someone whose development was straightforward, even a little boring. I arrived at Gagosian’s large upstairs gallery on Madison Avenue with low expectations of a thick array of Diebenkorns in that one room. Maybe it had been a mistake, inspired by misguided nostalgia, to take on this assignment. In the event, the exhibition was revelatory, holding me spellbound. This is one reason why I love being an art critic – the surprise.