I was on a long flight recently, the over-night type where you’re never quite sure what time it is, and you don’t know how long you’ve been sleeping, but you know for sure you won’t be going back to sleep anytime soon. So, I rifled through the seat pocket in front of me for some headphones and plugged in to see what was playing on the television screen.

I had low expectations but soon discovered something to stay awake for, a documentary called “The Philosopher Kings” directed by Patrick Shen. I realize the film was made in 2009, and I’m behind in discovering it, but I believe it’s worth some better-late-than-never attention.

The film follows eight custodians working at universities around the country—schools like Cornell, Duke, Princeton and U.C. Berkeley where becoming a custodian might not be the goal of many students—and documents the insights they have gathered throughout life.

There is Melinda Augustus who looks after a university museum and marvels at the carefree existence she finds in the butterfly exhibit. There is Corby Baker, an artist who cleans for an art institute and works on his own projects during off hours. There is Oscar Dantzler, the custodian for Duke Chapel, who learned from his mother, “If you can’t keep the house of God clean, you ain’t gonna keep no place clean.”

And there is Jim Evener, a former rodeo rider and wounded Vietnam veteran who cleans classrooms and labs. “It’s a learning opportunity every day,” he said, whether he’s learning from students, professors or coworkers. His philosophy: “If you’re miserable every day, you’re doing something wrong. I’m actually happy with what I’m doing right now.

The custodians tell their stories of adversity and successes. They talk about healing, relationships and forgiveness, education, the importance of self-confidence and personal pride, about making the most of every opportunity and about doing justice in life. And they talk about rising above the misperceptions people often have of custodians, the assumption that someone takes the job because they have no other choice. “Most of them have a preconceived notion of who you are when they see you pushing a trash can or see you dragging a mop bucket,” said Michael Seals of Berkeley.

The director of “The Philosopher Kings” was “in search of wisdom found in unlikely places,” according to his own synopsis of the project. Initially, the premise seemed patronizing to me, but after just a few minutes of watching the film, I understood his point. All too often, we rank each other according to occupation, but we should not be surprised to discover wisdom from someone who sweeps floors. We should not presume the custodial department, or any department for that matter, is an unlikely place for insight.

The structure of the documentary helps make this point very clear—each segment is introduced with a quote from an established writer or philosopher, someone who wouldn’t surprise you with some amount of insight. You expect to learn something from the likes of Emerson, Shakespeare, Socrates or Sartre. By the end of this film, you also expect to learn something from the likes of custodians.

The wisdom of Luis Cardenas becomes equal to that of Plato. Melinda Augustus stands side by side with Graham Greene in her insight. And Gary Napieracz can be as perceptive as Joseph Campbell.

After watching the film, you come to respect this custodial wisdom, and you recognize that we each have learned lessons from our varied experiences and have a story to tell. Each story is as important a thread in our collective tapestry as the next, and what we do to earn a paycheck does not add to or take away from that importance.

You can watch “The Philosopher Kings” online anytime at www.philosopherkingsmovie.com. I recommend it, and make sure to catch the final screen, a quote from Plato that reads, “There will be no end to the troubles of states, or indeed of humanity itself, till philosophers become kings in this world or till those we now call kings and rulers really and truly become philosophers."

Or, as Josue Lajeunesse from Princeton said, “I believe everybody deserves to live right.”