After decades of faithful repetition, the annual intellectual flagellation of Thanksgiving has become a tradition all its own, as seemingly indispensable as turkey or pumpkin pie. But despite the many things for which we need or ought not be grateful, gratitude is yet a virtue. In the story of the First Thanksgiving we find an example of something for which all Americans can and should be grateful—all the more, perhaps, for its contested role in American civic enterprise. I am speaking, of course, of American liberalism. Most any American grade-schooler can tell the basics of the tale: one year shy of four centuries past, in November of 1620, a ship of Saints and Strangers arrived at what we now call Cape Cod. Difficulties faced during their trans-Atlantic voyage dissuaded them from pressing on to their intended destination in Virginia; instead, most of the passengers remained aboard the Mayflower while some scouted the territory. The land was inhabited, albeit sparsely, by natives who made no show of hostility but also evaded any attempts at contact. What …