How do make sure that the lessons learned from Sept. 11 endure. After all, look at Pearl Harbor and those lessons.

That’s an insightful question.

Pearl Harbor hasn’t been forgotten, but it has become history, while 9/11 remains living memory for many people.

Several factors determine whether the lessons of a tragedy endure:

1. Living memory vs. historical memory

Millions of Americans alive today personally remember where they were on September 11, 2001. Many victims’ families, survivors, first responders, and military veterans are still alive and active in public life.

By contrast, the number of Pearl Harbor survivors is now very small. As generations pass away, memories naturally shift from personal experience to history books and museums.

2. 9/11 continues to shape daily life

Many changes that followed 9/11 are still visible today:

• Airport security procedures
• Intelligence and counterterrorism programs
• The Department of Homeland Security
• Military conflicts and foreign-policy decisions that followed the attacks

Because people still encounter these effects, the event remains relevant in a way that Pearl Harbor’s immediate consequences do not.

3. The attacks were witnessed in real time

A unique aspect of 9/11 was that much of the world watched it happen live on television. The second plane striking the South Tower was broadcast globally, creating a shared experience for millions of people. The images became part of collective memory in a way few historical events have.

Pearl Harbor occurred in an era before live television coverage, so most Americans learned about it after the fact.

4. The lesson evolves

The lesson of Pearl Harbor was initially “be prepared” and “don’t underestimate threats.” Over time, that lesson became institutionalized into military planning and national defense.

Similarly, the lessons of 9/11 may eventually become less emotional and more institutional:

• vigilance against terrorism
• emergency preparedness
• interagency cooperation
• resilience after disasters

Future generations may study 9/11 the way today’s students study Pearl Harbor.

5. Neither event should be remembered through fear alone

The most enduring lesson from both events may not be about the attacks themselves, but about the response:

• Courage under pressure
• Sacrifice for others
• National unity during crisis
• The importance of defending democratic values

Those themes are why both Pearl Harbor and 9/11 continue to be commemorated decades later.

In fact, many historians draw a direct comparison between the two events. Both were surprise attacks on the United States that dramatically changed American foreign policy and led to long military campaigns. The difference is mainly one of time: Pearl Harbor is 85 years in the past, while 9/11 is 25 years in the past. If history is a guide, 9/11 will likely transition from a personal memory to a historical memory over the next several generations, much as Pearl Harbor did.