1972: The musical Grease opens on Broadway. It is a nostalgic look at the 1950s, and a prime example of the 1970s obsession with nostalgia in entertainment.

Today: Grease has been revived for several years on Broadway. There is now nostalgia for past nostalgias.

1972: There is an enrollment decline in Catholic schools in favor of public institutions. Numerous parochial schools close, in part because of funding problems. Those that remained have problems finding staff. Many believe that a Catholic school does not offer as good an education as a public school.

Today: Public schools are under fire for not providing a solid education for students. Many parents turn to parochial schools, charter schools, and other private institutions, believing they offer a better education and better discipline.

1972: The Watergate break-in occurs. Five men break into the Democratic National Committee's offices to spy on the committee, an...