Please read the Scripture passage before the homily.
People seemed to have recognized Jesus as a teacher, one like John the Baptist or like one of the Pharisees. Hence the question to Jesus why Jesus had not taught his pupils, or disciples, how to fast the way other headmasters had taught their students or disciples.
It was like asking Jesus why he did not teach flying propellered planes and instead taught jet engines. It was like putting new wine in new skins instead of using old skins. It was like teaching how to celebrate weddings instead of teaching etiquette proper for funerals. Something/Someone new was present and times were changing. The present was becoming a time of newness and the old was passing away.
When God comes down to live among us, as we believe God did in Jesus, then life has changed for us. Now it is possible for to see God in action. It is like opening a new school, one with different goals, different emphases, different methods, and better results.
Now there are three schools, a good one with religious emphasis, another proclaiming the need for repentance, and the third represented by Christ. Which will you choose? From which would you want your diploma or degree? Be a disciple or a pupil of Christ and you will get a new view on reality and a new destiny overall. It is now for you to choose your school.