It was a symbol of how they should act towards each other and towards others. The four evangelists all have descriptions of a last supper of Jesus with his disciples. Three of the Evangelists describe the cultic institution of the Eucharist. The fourth evangelist, John, describes Jesus washing the feet of his disciples, a description of Eucharist in action, a mutuality of service. As I have done for you, so you must do for others.
Eucharistic worship is balanced by Eucharistic service.
Indeed, the deepest significance of Eucharist is service towards others. Eucharist in the Franciscan tradition is the point at which worship and service meet. This homily was given by Jackie Stewart at the Twilight Retreat at St. Anthony Shrine held on March 7, 1997. The theme of the retreat was Eucharist in the Franciscan Tradition. The photo of Jackie was taken in the olive groves of San Damiano, Assisi.