No incident in recent times has shocked the nation's senses like the mindless slaughter of 20 six- and seven-year-old children and six of their unarmed adult defenders at the Sandy Hook Elementary School in Newtown, Conn.The president, fighting to hold back his own tears, said much of what many of us have been thinking. There have been entirely too many of these outrageous and unprovoked slaughters of innocents. The 181 separate gun incidents in America's schools in the short years since the Columbine disaster have shaken us into unprecedented outrage.Can't we in this enlightened age collectively find ways to stop the senseless repetition of behavior so essentially, we'd like to think, "un-American?"Each time a serious effort is launched to control such insane misuse of firearms, opponents raise the Second Amendment. It clearly wasn't written to protect armed assaults on innocent Americans!The authors' original purpose was not ambiguous but clearly stated. It involved national defense. The entire provision contains just 27 words: "A well regulated Militia being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed."The amendment's authors, writing in 1789, clearly wanted American farmers and ordinary householders to be able to respond the next time a patriotic Paul Revere came around wanting armed help to repel an attempted British invasion.These, the ordinary residents, were all we had to comprise a "militia." If robbed of weapons to defend their modest homes and villages, the nation would've been easy prey to a well-armed invader.That logic probably made good sense in 1789. Today, it would be hopelessly outdated. Like other ideas of the time -- the idea that only male property-owners should vote, and the early compromise to count each slave in any future decennial census as exactly three-fifths of a person.Today, our "well regulated Militia" is not a bunch of well-meaning farmers with muzzleloaders but a system of highly organized National Guardsmen in every state of the union, subject to the president's call to federalization, and a "well regulated" standing system of trained Army, Navy and Air Force reservists.These, together with standing military forces, are what we depend upon to defend our free society from outside attack.There's a disturbing number of mentally maladjusted individuals who increasingly and without warning stride out of nowhere armed with deadly assault weapons to slay innocent children and unsuspecting adults in presumably safe public environments like schools, churches and theaters.Surely the 18th-century authors of the first 10 amendments could never have imagined, let alone confused that poisonous gaggle with their dream of a "well regulated Militia."The time, clearly, has long since arrived for sensible regulation of deadly assault and repeater firearms and dependable protection for the American public against their irresponsible misuse.Responsible American hunters and legitimate gun owners have no sympathy for the growing misuse of assault weapons.Beyond this, and independent of legal requirements, American society as a whole truly needs to depopularize violence and raise its standard, from childhood video games to championship sporting events.If this sounds like a lot to ask, consider how long the need has been developing.And if we're not able to take at least some corrective actions in face of this latest unspeakable disaster, when will we be?Jim Wright is a former U.S. House speaker.