The quote comes from "An Open Letter to the American People" New York Weekly Review, 17 February 1866, 1. The full quotation reads: "The most useful and interesting letters we get here from home are from children seven or eight years old. This is petrified truth. Happily they have got nothing to talk about but home, and neighbours and family--things their betters think unworthy of transmission thousands of miles. They write simply and naturally, and without straining for effect. They tell all they know, and then stop." Victor Fischer Mark Twain Project