PostSecret is a collection of anonymous postcards people sent to Frank Warren, who in 2004 printed 3000 postcards with his address on them, inviting strangers to fill them in and tell him their secrets. The response was so great, he didn’t have to print any more postcards. People sent their own, in various languages, including Braille. ‘Like fingerprints, no two secrets are identical.’ Reading is a kind of voyeurism. We always want to know more...