When the Japanese government was trying to eradicate Christianity, they made those suspected step on a picture of Christ or the virgin Mary. If they refused, they were arrested and tortured, and often killed.
The picture was called a "fumie." This is one example.
Today, I'm thinking about Judas, and Peter: and us.
I'm also thinking: what a simple act, to step on a picture. We would probably think: why would it be so terrible to step on a picture? But for those Christians it was denying their faith and betraying their Lord. They thought that anything that bore Christ's image was holy.
I'm also wondering: what or who else we might carelessly step on, without noticing that they too were holy?