PostSecret, a project that collects anonymous secrets mailed on postcards from around the world, is now a book.

Forbes has called Frank Warren “the most trusted stranger in America.” He started collecting secrets in 2004. Since then, he has received over 400,000 postcards, each inscribed with a secret. He has a website, and now a new book titled, “PostSecret: Confessions on Life, Death and God.”

The book contains some lighter secrets, but there are also some very dark things.

“Secrets hit every note of human emotion,” says Warren. “They can be funny, joyful, sexual, hopeful, or heavy, It makes me aware of everyday stories that we never get a chance to see.”

Almost all of the postcards submitted to PostSecret arrive anonymously. As some of these secrets are quite serious, Warren has taken the opportunity to provide some direction.

“When I get those, what I try to do is channel those feelings towards promoting 1-800-SUICIDE, the national suicide prevention hotline on the website. In fact, in five years, the PostSecret website/community has raised hundreds of thousands of dollars for Hopeline.”

For those that have sent in secrets, the reactions of having them published are mixed.

“Some people are thrilled, some people are terrified. In fact, I have had some people say that when they wrote down their secret on the card, they felt like they were making something up. But, when they took it to the mailbox, physically let it go, and then later saw it on the website, they realized there was a kernal of truth there.

“The whole process was a way for them to share a secret with themselves that they had been hiding from.”

“After you see 400,000 of them you think they would be the same, or similar; but every day they are full of surprises. It is almost like poems or songs. I don’t think we ever run out of them. They are inexhaustibile.”