Matthew 13:10-17 "The disciples came to him and asked, "Why do you speak to the people in parables?" He replied, "The knowledge of the secrets of the kingdom of heaven has been given to you, but not to them. Whoever has will be given more, and he will have an abundance. Whoever does not have, even what he has will be taken from him. This is why I speak to them in parables: "Though seeing, they do not see; though hearing, they do not hear or understand. In them is fulfilled the prophecy of Isaiah: " 'You will be ever hearing but never understanding; you will be ever seeing but never perceiving. For this people's heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.' But blessed are your eyes because they see, and your ears because they hear. For I tell you the truth, many prophets and righteous men longed to see what you see but did not see it, and to hear what you hear but did not hear it.
Jesus explained that He used parables so that the hearts of those rejecting would not be hardened further. The same sun that softens the wax hardens the clay; and so the very same gospel message which breaks down honest hearts and leads to repentance, hardens the hearts of the dishonest and confirms them in their path of disobedience.
Therefore I speak to them in parables, because seeing they do not see, and hearing they do not hear, nor do they understand: In this sense, the parables of Jesus were not illustrations making difficult things clear to all who heard. They were a way of “encoding” God’s message so the spiritually sensitive could understand, but the hardened would merely hear a story without heaping up additional condemnation to themselves for rejecting God’s Word.
And in them the prophecy of Isaiah is fulfilled: By speaking in parables, Jesus also fulfilled the prophecy of Isaiah, speaking in a way that the hardened would hear but not hear and see but not see.
But blessed are your eyes for they see, and your ears for they hear: In light of this, how blessed are those who do understand the parables of Jesus. Not only do they gain the benefit of the spiritual truth illustrated, but they also display some measure of responsiveness to the Holy Spirit.
Parables generally teach one main point or principle. We can get into trouble by demanding that they be intricate systems of theology, with the smallest detail revealing hidden truths.
"But Jesus recognized, as the Parable of the Soils clearly implies, that some were hostile or indifferent to His teaching. He knew that human soil, stubbornly refusing a harvest, falls under heavier indictment with each fresh sowing; that privileges abused confirm the abusers in their disobedience. He knew also that no good purpose is served by heedlessly exposing truth to mockery . . . Thus, in respect to the obdurate, the parabolic method was twice blessed: By veiling truth, it guarded it from raillery; and the hostile received despite themselves, a story that might germinate in secret, but which did not confirm hostility and deepen guilt, as a plainer statement might have done, by provoking enmity to wrath." (George Buttrick, The Parables of Jesus)