We spent last night at Powell Hall, the acoustically-perfect home of the St. Louis Symphony, who performed the score of Charlie Chaplin’s 1931 “City Lights” while the movie was projected on a screen overhead. We saw them do this a couple of years ago, with Chaplin’s “Modern Times,” and we marveled at the experience both times.

The movie itself is a classic, but what made this showing so remarkable was that, after awhile, my wife and I both found ourselves forgetting that there was even an orchestra in the room. That’s not an insult to the Symphony or conductor David Robertson. It’s a compliment to their ability to synchronize so perfectly with the film. I had to shake my head and look away from the screen a couple of times to remember to look down at the orchestra as they played furiously in the dark, with the only illumination coming from tiny lights atop their music stands.

Orchestras play along with movies all the time, of course, but not the entire score in one sitting. When they’re hired to add music to a movie, they do it in individual takes for separate scenes in a recording studio, with digital editing and audio enhancement making everything sound just right. But when a Symphony plays the score at events such as this, there is no second take, no opportunity to fix mistakes, which is the inherent thrill of hearing live music.

Since Chaplin’s score is so dense, there were virtually no breaks where the Symphony wasn’t playing — for nearly 90 minutes — and it was flawless. They deserved the three curtain calls and standing ovation they received last night.

As for the movie, which will be 80 years old next month, it contains one of the best-choreographed comedic sequences ever filmed. Chaplin’s Tramp has fallen in love with a blind flower girl who lives with her grandmother. They’re behind on the rent and have to come up with the money by the next day or they’ll be evicted. Chaplin vows to help, but after being fired from his job as a sanitation man, he’s desperate for any opportunity. A local boxer corrals him to come into a gym and fight in a winner-take-all bout, but since the boxer isn’t very good, he wants to make a deal — if Charlie will allow himself to be knocked out quickly and easily, they’ll split the prize money. Unfortunately, the cops are after the boxer, who runs away before the match, and is replaced by a big, brooding thug who has no interest in the cash-sharing deal.

What makes all this more remarkable is that Chaplin not only starred in “City Lights,” but also wrote, directed, edited, and scored the movie.