In our nation's capital, it has become more difficult to get from Capitol Hill to Georgetown. The reason, of course, is the need to take a detour around that anachronism on Pennsylvania Avenue. Why do I call the President's lovely mansion an anachronism? Is it necessarily anachronistic to have a stately country home sitting in the middle of a bustling modern city? That kind of anachronism we call "charm." What doesn't fit between this place and our times is the growing difficulty of keeping its occupant --our head of state-- from being murdered.

The obvious part of the problem involves changing technology: this late eighteenth century estate is not well matched to the armamentarium available to the late twentieth century assassin. Kamikaze pilots of small airplanes. Automatic weapons. Massive truckbombs made of common agricultural chemicals. And all of this readily available to hundreds of millions of people, including a veritable "Joy of Blasting" book of recipes for explosives on the Internet. But technology isn't the whole thing.

There has also been a profound shift in the moral realm: our president is in greater danger because we have plunged into an age without taboo. Time was, the killing of a king was practically unthinkable. Centuries of cultural development had hedged round the ruler with a nimbus of inviolability. It was ingrained into the civilized psyche that one does not assault the king. Not that it never happened -- taboos exist because of the impulse to violate them -- but when it did it was as though the earth shook. England still reverberates from Cromwell's beheading of his king; and we in America continue to shake from that shocking day in Dallas more than thirty years ago.

But that was then. What's unthinkable now, when a talk show host gets stellar ratings boasting that he uses portraits of the president and his wife for target practice? When every night on the news the most unspeakable acts are spoken of, at length? When people line up to parade their incestuous relationships on national TV?

In our time, the walls of taboo have been stormed, like some oppressive Bastille, to release our darkest impulses into the light of day. As we wait to see if this new openness can be integrated with decent moral order, we are compelled to live at a time of heightened danger, where the once unthinkable seems almost inescapable. These new barricades of concrete in front of the White House look to me like tangible replacement for the less tangible walls in the moral realm that we have been tearing down.