What’s the quietest thing you’ve ever witnessed?

I was just sitting on my porch at 5:47 a.m., coffee cold, when I noticed the city hadn’t quite woken up yet. No traffic, no sirens—just the faintest rustle of a paper bag caught in a gutter. It wasn’t even wind. I sat there wondering if that was the quietest thing I’d ever heard, or just the most honest. What’s the silence that stayed with you?