Like 12/7 (Pearl Harbor), 9/11 lives in infamy.

Both tragedies were tough lessons in strategic surprise, and both were the result of grievous intelligence failures.

The warning is obvious only in hindsight, but in his January 2001 Senate confirmation hearings Donald Rumsfeld recognized the problem. When asked if he would name "one thing" that "kept him up at night" more than any other specific threat or trouble the Pentagon confronts, Rumsfeld answered, "Intelligence."

In a column of mine published on Jan. 23, 2001, I wrote that "Rumsfeld's response fingered what is the major American foreign policy and defense weakness, even in this era of extraordinary American economic, political and military strength. Faulty and inadequate intelligence is not merely a source of current SecDef sleep deprivation, it has loomed large in real world nightmares, from Pearl Harbor to Korea to Vietnam to the USS Cole disaster."

That column also added: "Fielding human spies (HUMINT in the jargon) is a delicate, time-consuming and often dirty business. Tightly knit terrorist cells, however, can evade high-tech detection. Stopping Osama bin Laden means America has to have more and better trained agents."

Yes, that's pre-9/11.

The sixth anniversary of 9/11 is an appropriate moment to reflect on the vexingly complex problem of surprise, and particularly strategic surprise. The problem has no solution, at least no perfect solution. Unless you know the future, surprise is inevitable.

Limiting the more devastating effects of surprise is the elegant trick that defines the best-prepared. I think the insurance industry uses the term "lowering the risk premium." That means limiting the number of lives lost, the property damage and the costs of assuring security.

Last month, the CIA inspector general's office released its assessment of the CIA's pre-9/11 efforts. The report was damning. The CIA had sources, leads and facts, but it lacked imagination -- the dynamic imagination to foresee al-Qaida's planned attack.

The CIA is a bureaucracy. Bureaucracies are hell on artists, which is OK if you're pushing pencils but not OK if you are puzzling through an intricate design. The 9/11 plot was an intricate design.

Intelligence is an art -- a grand, interpretive collusion of linguistics, geography, mathematics, history, theology, psychology, physics, metaphysics and every other human means of analysis and explanation. Former CIA Director James Schlesinger nailed it in October 2003 when he said: "But major organizational change (of U.S. intelligence agencies) is not the salvation. I would submit the real challenge lies in recruiting, fostering, training and motivating people with insight."

Insight. If that sounds artsy, well, it is. Continued...