At about 11:30 a.m. yesterday, a police officer told me and about eight other students that, and I quote, “the grass is closed.” We were going to sit under a tree and discuss things, and two police officers were watching us vigilantly to make sure we didn’t suddenly do something violent like try to put up tents. As we moved towards the tree, the first police officer stepped up and informed us that we could not walk from the broad concrete steps of Sproul Hall, where about a hundred people were sitting and talking, and sit on the grassy area just to the north of it. “The grass is closed,” she said.If you meditate on these words until they become a mantra, you will learn some profound things about how police authority works. What could it possibly mean to declare that “the grass is closed”? Who could have the authority to say so? I had always considered that stretch of grass to be public; I’ve often been among the hundreds of students who eat their lunch there, every day, and 11:30 a.m. is a time of day when it is common to eat lunch. I have had conversations with other students sitting on that very grass, many times. Why was it that I could not do so now? Why had this stretch of grass suddenly become un-public and closed off? No signs said so, and no police tape marked it off. At the far end of that grassy area, in fact, several people were actually sitting on the grass. But those people were sitting there eating lunch. Because we were part of the group which was sitting on the steps of Sproul Hall, clearly, the grass had been declared off limits to us.