A seventh century Spanish liturgy was the first to use it on Maundy Thursday. Lutheran congregations have the choice to use it on that day as well. When we do, we quickly recognize the many meanings feet have for us. We consider them sensitive and silly appendages. People don't want to expose them.
Feet get knobby and worn.
They are covered with protruding veins, bunions and calluses. It's an unfamiliar intimacy. When Jesus washed his disciples' feet, Peter refused this gift. Peter, like us, didn't want to be served in this way. Nor did he want to change places with Jesus.