In verse 4 it says that Jesus laid aside His garments. He removed His robe and replaced it with a towel. You know, the towel he is talking about is like an apron, and it was used to protect the servant from splashing water and getting dirt on themselves. But here we have some beautiful imagery. Because we see, here, Jesus divesting Himself of His role as Lord and Master and becoming a servant. Christ was taking on the role of a servant because that was His purpose for coming to the earth for the first time. He came to serve all of mankind.
Brethren, it is important that we stop here for a second and understand something. Jesus Christ washed the feet of even the man who was going to betray Him, and He knew who that man was.