In relating the episode of Jesus washing His disciples' feet, John is attempting to explain the inner meaning of Jesus' ensuing death. This death will be the final expression of His love for His disciples, the seal set on a life-time of service. To wash someone's feet is a sign of humble service, the work of a slave. Jesus behaves like a slave towards His disciples, in order to show that His mission is one of service which has no bounds. Peter's horrified reaction to His Master's behaviour is an indication of the difficulty some experience in accepting humble service.

Jesus explains His behaviour to His disciples as an example which He invites them to imitate. Just as He has really washed their feet, as a sign of His service, so they should, metaphorically, wash one another's feet by serving one another. The washing of the disciples' feet is a practical demonstration of the "new commandment" (Mandatum - hence "Maundy") which Jesus subsequently gives to His disciples. They are to do to one another as He has acted towards them, to "love one another; even as I have loved you" (Jn. 13:34).