America is an improbable idea. A mongrel nation built of ever-changing disparate parts, it is held together by a notion, the notion that all men are created equal, though everyone knows that most men consider themselves better than someone. "Of all the nations in the world, the United States was built in nobody's image," the historian Daniel Boorstin wrote. That's because it was built of bits and pieces that seem discordant, like the crazy quilts that have been one of its great folk-art forms, velvet and calico and checks and brocades. Out of many, one. That is the ideal. The reality is often quite different, a great national striving consisting frequently of failure. Many of the oft-told stories of the most pluralistic nation on earth are stories not of tolerance, but of bigotry. Slavery and sweatshops, the burning of crosses and the ostracism of the other. Children learn in social-studies class and in the news of the lynching of blacks, the denial of rights to women, the murders of gay men. It is difficult to know how to convince them that this amounts to "crown thy good with brotherhood," that amid all the failures is something spectacularly successful. Perhaps they understand it at this moment [in the aftermath of 9/11], when enormous tragedy, as it so often does, demands a time of reflection on enormous blessings. A. The first paragraph discusses the aspects of American culture that unify Americans. The second paragraph discusses the aspects of American culture that tear Americans apart and cause friction.

B. The first paragraph discusses the idea that Americans are united as one despite their differences. The second paragraph discusses the idea that acts of intolerance make it difficult to believe that Americans are united as one.

C. The first paragraph discusses possible benefits to living in a society like America. The second paragraph discusses the disadvantages of living in a society like America.

D. The first paragraph discusses the diversity of American society and its role in history. The second paragraph discusses the uniformity of American society and its role in history.