12 So when He had washed their feet, taken His garments, and sat down again, He said to them, "Do you know what I have done to you?
13 You call Me Teacher and Lord, and you say well, for so I am.
14 If I then, your Lord and Teacher, have washed your feet, you also ought to wash one another's feet.
15 For I have given you an example, that you should do as I have done to you.
16 Most assuredly, I say to you, a servant is not greater than his master; nor is he who is sent greater than he who sent him.
17 If you know these things, blessed are you if you do them.
Teacher and Lord (v.13) = (in Greek) the Teacher and the Lord. Christ knew and claimed His greatness.
In the New Testament, no follower of Christ ever referred to Him as simply "Jesus."
wash one another's feet (v.14) — symbolic of service (love and humility). Nowhere else in Scripture is foot-washing mentioned except 1 Timothy 5:10 where it is simply as act of hospitality.
The symbolic meaning (Matthew 20:26-28; Galatians 6:1) — cleansing of dirt from our walk
Verse 16 — be subservient, esteem others as better
Why hadn't the disciples already washed each others' feet? The answer can be found in Luke 22:24-27, which took place during the same meal.