In John 13:34-35 we read: I give you a new commandment: love one another. As I have loved you, so you also should love one another. This is how all will know that you are my disciples, if you have love for one another.”
“Jesus represents the whole of his saving ministry in one symbolic act” ….It “signifies the whole of Jesus’ saving ministry”…”this humble gesture expressing the entire ministry of Jesus’ life and death…”
(J. Ratzinger, Jesus of Nazareth, p. 57, 72, 74; see “The Washing of the Feet” pp 53-75)