Social progress can seem painfully slow. And then, almost out of nowhere, events bring public opinion and the law together to produce head-spinning change.
This month will go down in history as one of those epic tipping points on several issues that have simmered below the surface of American society for generations.
The U.S. Supreme Court ruled 5-4 Friday that same-sex couples in all 50 states have a constitutional right to marry. It was a landmark decision against discrimination that followed a seismic shift in public opinion toward gay rights.
Just a few years ago, gay marriage would have seemed unthinkable to most Americans. It was contrary to tradition and conservative religious beliefs, which were reflected in federal and state law.
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But when the legal question finally reached the nation's highest court, there was little doubt about the outcome. The legal arguments against same-sex marriage were almost laughably lame.
Equal protection under the law is one of this nation's most cherished values. The Supreme Court majority correctly decided that gay people should not have their freedom to marry blocked by other people's religious beliefs.
It was public opinion, not a court ruling, that swiftly turned the tide on another issue: state-sponsored veneration of the Confederacy, which has disrespected black people and fueled racial tensions since the Civil War.
Conservative politicians across the South were tripping over each other last week to call for removing Confederate flags from their state capitols, Confederate emblems from their state flag and license plates and statues of Confederate heroes from places of honor.
It was a stunning reversal. Many of these politicians, and others like them, had resisted this for years. Their predecessors helped erect these symbols, either to memorialize a mythical "Lost Cause" or to express defiance against federal civil rights legislation and court-ordered integration.
Then, suddenly a heinous crime exposed these excuses and rationalizations for what they really were. A 21-year-old white man murdered nine black worshipers in a Charleston, S.C., church after touting his racism online with pictures of himself holding the Confederate flag.
Many white people defend Confederate symbols as expressions of "Southern heritage." They view them as honoring the sacrifices of ancestors, most of whom did not own slaves and were fighting out of loyalty to their home states.
But these symbols have always had a different meaning for black people. Confederate leaders considered their ancestors to be less-than-human property, and they went to war to try to keep them enslaved.
Since the Civil War, white supremacists have often used Confederate imagery as a tool for trying to keep black people "in their place." Celebrating the Confederacy for other reasons does not change that bitter fact.
That doesn't mean every Confederate relic should be banished to a museum. But government, which serves all people in this increasingly diverse country, should be careful about how and where the Confederate legacy is enshrined.
Should Confederate President Jefferson Davis' statue be moved from the state Capitol rotunda to a museum? Should statues of Lexington's most prominent Confederate leaders, John C. Breckinridge and John Hunt Morgan, be removed from the old courthouse lawn and Cheapside?
A monument honoring the hundreds of slaves sold on the auction block at Cheapside or whipped on that courthouse lawn now seems more appropriate.
How do we preserve, acknowledge and learn from our complex history, while at the same time honoring values we want to shape our future? It is a delicate balance.
The last major tipping point this month has received less attention, but it was a watershed nonetheless.
Pope Francis issued a strongly worded encyclical to the world's 1.2 billion Roman Catholics that clearly framed environmental stewardship, climate change and related topics of social justice and economic inequality as moral issues.
But the leader of the world's largest Christian denomination will have a fight on his hands. His views are well-grounded in Christian theology, but they run counter to the way the world works.
Many powerful people worship a God found in bank vaults rather than Heaven. By shifting the moral conversation from sex to money, Pope Francis has made a lot of people nervous. It will be interesting to see what difference his leadership makes.
As the Rev. Martin Luther King Jr. famously said, "The arc of the moral universe is long, but it bends toward justice."