It sometimes seems strange that Jesus did not make His message transparently clear to all the crowds.  But He was not trying to gain a following.  Indeed, the more He taught, He seemed less like a popularist leader who would meet their needs, than a Man on a mission from God – following Him could demand too great a price (John 6:60-66).  But some did keep on following Him: the disciples who were being equipped to be apostles.  Although many ordinary people benefitted from His kindness and powerful miracles, it was the trainee apostles who stored up what Jesus did and said for their job of leading and teaching the church.  Under the Holy Spirit's guidance, their experiences with Jesus shaped the 'Apostles teaching' (Acts 2:42) which is the source of all true doctrine.  

True learning comes from an enquiring mind and a willing heart.  Jesus' parables and miracles caused the disciples to think and ask questions (John 16:17-18).  There were riddles to be answered, and pictures to be explained.  Illustrations help us learn. Without prior experience, we can only understand something by reference to something we know.  The parables provided that link - between the rural economy of His hearers, and the Kingdom, which was home to Jesus.  Each parable usually only paints a small part of the picture - but enough for people to have their desire for God's truth stirred.  And Jesus did not make it complicated. 

When God talks to people, He talks personally.  Although the seed of God's Word is broadcast, the Lord knows where each Word goes; each has a specific target.  He does not lecture us three grades higher than our capacity, but feeds His Word to us, as much as we can understand (1 Peter 2:2).  Of course, Jesus intended that the disciples would learn more: so He amplified the parable stories in private, and explained their eternal meaning to His trainee apostles.

In almost three years, the disciples were taught the 'secrets of the kingdom' - as much as they could understand at the time – leaving the Holy Spirit to complete their training after Pentecost (John 14:26).  Sometimes the Lord properly chided their refusal to apply what they had heard (Matthew 17:17).  Their privilege, like ours, was to spend time alone with Him - time to reflect and ask questions, time to get to the root of God's answers (Luke 10:38-42).  Private time with the Lord is the commodity most likely to be squeezed in our busy lives - but without it, our understanding of the most important business ever, will be defective ... and so will we.