Why did Lynne Truss’s book on punctuation become such a major hit in the UK? “Among the legions of the surprised are the executives at her publishing house, Profile Books, who ordered a modest initial printing of 15,000 books, but now have 510,000 in print; and Ms. Truss’s friends and family.” But why is it such a phenomenon? “Maybe Ms. Truss has indeed touched a nerve of latent pedantry in a world in which, as she writes, increasing numbers of people ‘don’t know their apostrophe from their elbow’.”