St. Ambrose has a very thought-provoking exegesis on the footwashing in John 13 – icon of Christ’s diakonia – as the mutual sanctification of kerygma. It’s not just the Gospel message, but it’s the “water of the message,” the “heavenly dew” of divine love making our minds and hearts fruitful for Him. To wash feet in imitation of Christ means to proclaim the Gospel in such a way that, in oneself and in those who hear and accept the Gospel, holiness of life and intimacy with Christ result. Notice how the Liturgy of the Hours and lectio divina are even more fundamental to this sanctification than baptizing (!!). He’s thinking of himself as bishop, of course, and the fundamentals of fulfilling his ministry with all seven sacraments and the whole “triple munera.” But I think the same must also apply to those who share the duties of the bishop in the degree of the diaconate.
“How great is that excellence! As a servant, You wash the feet of Your disciples; as God, You send dew from heaven. Nor do You wash the feet only, but also invite us to sit down with You, and by the example of Your dignity do exhort us, saying: You call Me Master and Lord, and you do well, for so I am. If, then, I the Lord and Master have washed your feet, you ought also to wash one another’s feet (Jn 13:13-14). I, then, wish also myself to wash the feet of my brethren, I wish to fulfill the commandment of my Lord, I will not be ashamed in myself, nor disdain what He Himself did first. Good is the mystery of humility, because while washing the pollutions of others I wash away my own…. It is not, then, the simple water of the heavenly mystery whereby we attain to be found worthy of having part with Christ. There is also a certain water which we put into the basin of our soul, water from the fleece and from the Book of Judges; water, too, from the Book of Psalms. It is the water of the message from heaven. Let, then, this water, O Lord Jesus, come into my soul, into my flesh, that through the moisture of this rain the valleys of our minds and the fields of our hearts may grow green…. You have redeemed the world, redeem the soul of a single sinner. This is the special excellence of Your loving-kindness, wherewith You have redeemed the whole world one by one.” (On the Holy Spirit, Book I.14-17)