Whenever an event grips the nation’s attention, the media inevitably turn to historians to offer some perspective.  From the disputed 2000 presidential election, to the 1991 Los Angeles Riots, to the recent Microsoft antitrust case, historians have been asked to help Americans see the precedents and parallels to the events of our times.  Often what people seek from historians is some assurance that the nation has endured similar episodes of national trauma and managed to persevere.  Unfortunately, in the case of Tuesday’s horrific acts of terrorism, historians have little to offer. 
     Still, some have tried.  The most irresistible historical comparison is to the Japanese attack on Pearl Harbor on December 7, 1941.  The high casualties (2,400 killed) and national outrage produced by a surprise attack on U.S. soil suggest a clear parallel with Tuesday's attacks.  Yet the events are dramatically different.  Unlike Tuesday’s terrorist strikes, the attack on Pearl Harbor was an act of war carried out by a clearly identifiable enemy.  Furthermore, it produced a logical and conclusive response: a declaration of war followed by an eventual victory.  Few Americans in 2001 can expect a similar outcome. 
     When considering sheer carnage, some might be tempted to draw historical parallels between the recent attacks and major urban disasters.  In 1900 a massive hurricane leveled the city of Galveston, Texas, killing at least 8,000 people.  Six years later a devastating earthquake in San Francisco claimed an equal number of victims.  These comparisons end with the numbers, however, because unlike the man-made horrors of Tuesday, most Americans understood these events to be "acts of God," clearly beyond the control of mere mortals.  They wept and prayed, but no one seriously questioned the nation’s overall security.
     In terms of shock value, perhaps the closest historical comparison to the terrorist attacks is the assassination of John F. Kennedy in 1963.  Like Tuesday’s assault, it caught the nation completely by surprise and, given the context of the Cold War, elicited widespread fear of a wider conspiracy.  Still, the differences far outweigh the similarities.  First, in contrast to the thousands who perished this week, Kennedy’s assassination represented the death of a single man (albeit an important one).  Second, as time wore on, the assassinated president acquired an almost saint-like image of youth, vigor, and optimism  that shows no sign of waning.  We can hardly expect any such inspiring mythology to emerge from this week’s events.
     In most cases, historical perspective allows us to see wars, natural disasters, and assassinations for what they are: ugly, but familiar aspects of the human condition.  Somehow that helps the healing process.  Tuesday’s extraordinary acts of terrorism, however, defy historical perspective because they don’t remind us of anything.  Rather, they announce a new, frightening, and unfamiliar reality of high-tech, international terrorism and our vulnerability to it. 
     History can offer no consolation here. These acts of terrorism are unprecedented in every way imaginable.  That’s the most terrifying thing of all.