Jesus holds out to his followers the apron he first put around himself. By serving them, the Master orders servants to remain so. Being called « his friends » (Jn 15,15) doesn’t free them from their work, but devotes them to the work of release Jesus carries out.
Joseph holds a special place in this service, as he always preferred God’s will, he has been named not only « friend » but also « father ». Therefore, if you imagine Saint Joseph kneeling in front of the little Servant to wash his feet, ant not only his feet but his hands and head, you have to understand that the saint patriarch takes part in the Resurrection’s work beside the whole Christ’s Body. This is his way to be forever kneeling at Christ’s feet.