Settling in to watch the extraordinary documentary called “9/11” on Sunday night, I was reminded of the conflicted emotions I felt when I visited ground zero.

As I walked with hundreds of others through that hallowed place over the Christmas holidays, the survivors and families of the victims of the World Trade Center attacks complained in the media that our presence there was ghoulish. They argued that the crowds streaming into lower Manhattan created a carnival atmosphere around what had become a solemn graveyard. To wander the area with cameras was to disrespect the memories of their lost friends and loved ones, they insisted. Didn’t we visitors understand that we were intruding on their personal grief?

A similar controversy greeted the announcement that CBS would air the documentary of two French filmmakers who had set out to make a human-interest story about a rookie New York City firefighter and wound up composing a chronicle of one of the most tragic moments in our history. In the days leading up to the program’s airing, CBS was reviled for being insensitive to the pain of the victims’ families. The station was accused of “trivializing a national tragedy.” Two New Jersey senators repeatedly urged broadcasters to be cautious about what they depicted, and a representative of one victim-advocacy group warned about “the potentially negative psychological effects that graphic details of death and destruction may have.” On a CNN segment that questioned the wisdom of airing the film, a woman whose mother died on one of the hijacked airplanes argued that it was too soon to show footage of “my mom’s plane blowing up.”

The emotions of the families are entirely understandable, of course. They have suffered since the attacks in ways that, blessedly, the rest of us have not. But contrary to their objections, the urge to visit ground zero, for most of the people who make pilgrimages there, is not motivated by morbid curiosity. We go there not for its lurid appeal, but rather to pay our respects to the dead, to mourn their loss and the loss of what we once were as a nation and will never be again. We go there to search for some measure of clarity, fleeting though it is, in the chaos that turned our world upside down.

And so it was, I would like to think, for the millions of us who warily tuned in on Sunday to get our first-ever glimpse into the tragedy as it unfolded. We came to the program not for the sensational but for the historical. For that is precisely what the film was meant to be – a harrowing, gut-wrenching, real-life historical record of what happened not just to the thousands who died but to all of us who are left to make sense of it. After all, it was not just one “mom’s plane” that blew up that day, it was a plane turned in the most horrific way against every American. It was not only a private tragedy for those unfortunate families, it was a nation’s tragedy, too. We all have a stake in it, and we grieve accordingly.

If six months after Sept. 11 is too soon to be exposed to such footage, or to visit ground zero, then when is the proper time? As a nation, we have moved on admirably since that day. We have donated our money and our blood. We have waved our flags, and we have sent our men and women to fight in inhospitable terrain so that the world might one day be free of the evil that threatens us still.

The film lets us finally become eyewitnesses to those acts of remarkable courage by firefighters that we had only read about in the months after 9/11. Every frightening image was a reminder of the depths of the terrorist atrocity, and why our American sons and daughters in Afghanistan are not fighting in vain. In allowing us to revisit the event, from inside the towers this time, the film provides a welcome opportunity to process the tragedy in ways that we never could have in those first anxious weeks.