dust in the sunlight

I was sitting on a bench with someone the other day when he pointed out that you could see the dust in the sunlight. He said he finds it interesting that there's all this stuff floating around that we can't see until the light hits it in a certain way. I thought it was a great metaphor--sometimes there is so much stuff floating around inside of us that nobody sees, that we don't even know is there, until the light hits it in a certain way--until somebody shines a light on it. And then suddenly that's all you can see. And it seems to surround you, and you wonder how you never saw it before--and maybe you wonder how you get out of it so you can breathe again.