"Confessions," opens Sept. 1, Third Street Gallery, 58 N. Second St., 215-625-0993, www.confess2.us

It's hard to keep a secret. But what if you could reveal one anonymously, without the risk of getting caught? Who wouldn't want to confess all to the world?

Venting on the Internet is common nowadays (see Grouphug.us), but the pen-and-paper way still seems more genuine and fun. Just pretend to update your diary: Brainstorm old and recent sins, crushes, wishes and teeny-tiny transgressions dying to get out (even, say, eating a roommate's banana). Jot them down, seal them up, slide them into a little box. No stamp necessary.

For a rather mysterious September installation, the Third Street Gallery is currently collecting anonymous confessions at 12 Center City locations, from the library to the Whole Foods to an Indian restaurant on South Street. (Check out the Web site's handy Google maps and updates, as one mailbox was recently destroyed.) Write long if you must; anything that fits through the slot goes. With any luck, the final work of art will be a wonderful, hideous composite of our city's most unspeakable thoughts.