The full quote is “Let nothing dim the light that shines from within,” and yes, it's from poet Maya Angelou, and isn't it pretty to think so? But the world being the world means we can't have pretty things. Here's the quote as it appears in the International District in Seattle:

A bit dimmer. I think a window got busted out, or a store went out of business—something had to be boarded up—and there went some of the quote. And then the modern poets started in on it. It's looked like this for a few years now.