Right now at David Zwirner Gallery, you can dip into one of the weirder artistic rivers of the last 40 years and behold -- or participate in -- On Kawara’s mad epic sculpture-performance One Million Years. The Japanese-born, New York-based artist’s rarely seen work is centered around a desk and two chairs in a windowed booth at the center of the otherwise almost empty Zwirner gallery. During business hours, two volunteers sit inside the room. One man and one woman take turns reading progressive dates going one million years into the future or into the past. Several Fridays ago, I spent an hour reading the 875 years between A.D. 38,658 and A.D. 39,533. It was one of the odder hours I’ve ever spent in a gallery.