Jesus taught the people only to the extent that they were Able To Hear.   

What is necessary to Hear?   
- Ears
- Interest
- Attention
- Reception

Now talkers don't really concern themselves too much with whether their audience is really listening to them or not.   They just love to talk.   

Jesus was a Teacher.   He Knew who He was.   He Knew the Truth because He is the Truth.   He was filled with the Holy Spirit who reveals all things.   

Jesus did not talk to hear Himself talking.   He taught so that people would Hear and Understand what He was saying.   

He wanted people to Repent so that they could experience the Kingdom Of God.   

Knowing how people are, I am quite sure that many of the people who thronged Jesus were not so much focused on what He was teaching as they were on Receiving a Blessing or seeing a Miracle.   

Jesus understood the Kingdom Of God and how it worked.   His Healings and Miracles blessed the people in need and excited the people who saw them, but they were transitory.   They met immediate needs but did not provide for the Future.   

His Teaching however provided for the immediate and Future needs of the people.   

So, Jesus Taught the people to the extent they were Able To Hear.   

The Holy Spirit is our Teacher today.   He is the same One who Taught Jesus.   But just as Jesus was only able to teach to the extent they were Able To Hear, so the Holy Spirit is restricted.   

This is why Jesus said "he that has ears to hear, let him hear".   He was talking about the kind of Hearing that produces Faith and a Transformed Life.   

We live in a Society of Hypocrites.   We Educate ourselves and our children to take on roles by which to make money, receive honor and wield power.   

But who are these people?   Are they just actors playing the part given them or are they more?   

Jesus did not concern himself with people's roles.   Fishermen, tax collectors, prostitures, thieves, it didn't matter to Him.   

He wanted to teach them about Grace, Faith and the Kingdom Of God.   He wanted them to Born Again.   

But when a person has a need they are interested in and paying attention to only that.   

Jesus healed and set Free in order to teach them the Love, Forgiveness and Power of God.   

But their background, understanding and attention limited what He could teach.   

Are you Able To Hear?   I suspect everyone's answer to this question is "yes" because perception is relative to experience.   E.G.   If you have always had bad hearing you don't know what good hearing is like.   

Our ability to hear must be exercised in order for it to be sharpened and our range increased.   

Note, Jesus was talking to His Disciples, the most 'taught' individuals of His day.   But He was ackowledging the fact that they were not Able To Hear some things that He wanted to share...    now .   He knew that when the Holy Spirit was poured into their lives they would be able to 'bear' them.   

Paul's Revelation of the Gospel by the Holy Spirit was radical and could not have nor would not have been received except that the Holy Spirit made the other Apostles Able To Hear the Revelation of Grace and Faith.