We've learned a lot about our nation in the four days since a 20-year-old walked into a Connecticut elementary school with a semiautomatic rifle and two handguns.
We learned, to our horror, that there are no limits to what a socially disconnected young man with too little conscience and too much ammunition will do to assuage his demons.
We learned that no matter how routine mass shootings become, there's always someone capable of going one step beyond what was once unthinkable. The men who squeeze the triggers are engaged in an invisible arms race fueled by psychosis, a desire for infamy and increasingly easy access to the same guns used to hunt the Taliban in Afghanistan.
The man who walks into a school, workplace, movie theater, mall or house of worship with the intent of killing strangers is usually someone who has spent too much time contemplating a skein of real and imagined slights.
We don't even have to know the particulars of the shooter's complaint to know that standing over the bodies of 20 children and six adults is disproportionate to any possible grievance. Even the bloodthirsty gods of the ancient Aztecs settled for one human sacrifice at a time.
We've learned that there are limits to even the National Rifle Association's shamelessness. We expected the NRA to quickly spin into action defending its radical interpretation of the Second Amendment as it has done after every other massacre, but it hasn't so far.
Wayne LaPierre, the face of the NRA, was missing in action the entire weekend. The void was filled by a chorus of outraged citizens and gun control advocates who vowed that the murderous anarchy represented by the status quo will come to an end.
While there were predictable mumblings from the ranks of stupider elected officials and pundits encouraging the arming of elementary school teachers, the NRA's highest-profile supporters in Congress kept uncharacteristically quiet, as if rendered mute by the sudden realization that military weaponry in the hands of ordinary citizens is an abomination.
Even media baron Rupert Murdoch is castigating politicians on Twitter about their cowardice for not having stood up to the NRA. When the godfather of conservative media sends a signal that enough is enough, then expect the tone at Fox News to begin a perceptible move toward the center on this issue.
We can all sense that something has shifted in the public discourse about gun control since Friday's massacre at Sandy Hook Elementary. For every spiritually bankrupt public figure who bellows that the absence of prayer in public school leads to school shootings, there are now thousands of voices of bipartisan reason and nondenominational sanity calling for greater gun regulation.
For the first time in years, politicians of all stripes are calling for the restoration of the assault weapons ban that lapsed during the second Bush administration. Those who were cowed into silence by the NRA are openly advocating not just a reasonable approach to the Second Amendment that honors the framers' intent, but a frank discussion about our violent popular culture and how draconian cuts to mental health services contribute to the carnage.
There's something about an unspeakable tragedy that can generate a perverse and ferocious eloquence from Americans about issues that have been ceded to extremists for too long. Where have these stirring voices of sanity and moderation on gun issues been all of this time? Why does it take so much blood on the floor for sound reason to make itself known?
President Barack Obama, who has been a disappointment on gun issues during his first term, found his voice Sunday evening in an address to the mourners in Newtown, Conn.
"No single law, no set of laws can eliminate evil from the world or prevent every senseless act of violence in our society," Mr. Obama said. "But that can't be an excuse for inaction." The president promised to use all the powers of his office to prevent similar tragedies.
"Because what choice do we have?" he said. "We can't accept events like this as routine. Are we really prepared to say that we're powerless in the face of such carnage? That the politics are too hard? Are we prepared to say that such violence visited on our children year after year after year is somehow the price of our freedom?"
Mr. Obama has made solemn speeches about gun violence before, but this one felt different. For the first time during his presidency, the majority of the country is with Mr. Obama on this issue. He might actually get something done now that enraged Americans strike more fear in the hearts of politicians than does the NRA.
Tony Norman: email@example.com or 412-263-1631. Twitter: @TonyNormanPG.