The Greek word translated "parable" is a compound word which comes from two words which mean "to throw beside." Jesus used a story that related to the audience's physical life in order to teach a spiritual truth.
"And the disciples came and said to Him [Jesus], 'Why do You speak to them in parables?' He answered and said to them, 'Because it has been given to you to know the mysteries of the kingdom of heaven, but to them it has not been given'" Matthew 13:10-11.
Why would Jesus want to hide truth from some people?
In Matthew 7:6, Jesus taught, "Do not give what is holy to dogs, and do not throw your pearls before swine, or they will trample them under their feet, and turn and tear you to pieces."
It wasn't that Jesus was hiding the truth, but more so that the teaching of a parable is a test in and of itself. Those who truly want to learn and understand will seek and ask and discover. Those who do not care enough will hear only and do nothing and therefore won't learn the spiritual truth Jesus embedded in the parable.
There are several examples in Matthew of the disciples not understanding the parable Jesus spoke to the people and them going and asking Jesus for a further explanation (e.g. Matthew 13: The Parable of the Sower, The Parable of the Tares and Wheat).
Further, in Matthew 13 following the before mentioned verses 10 and 11 Jesus said to the disciples, "Therefore I speak to them in parables; because while seeing they do not see, and while hearing they do not hear, nor do they understand. In their case the prophecy of Isaiah is being fulfilled, which says, 'YOU WILL KEEP ON HEARING, BUT WILL NOT UNDERSTAND; YOU WILL KEEP ON SEEING, BUT WILL NOT PERCEIVE; FOR THE HEART OF THIS PEOPLE HAS BECOME DULL, WITH THEIR EARS THEY SCARCELY HEAR, AND THEY HAVE CLOSED THEIR EYES, OTHERWISE THEY WOULD SEE WITH THEIR EYES , HEAR WITH THEIR EARS, AND UNDERSTAND WITH THEIR HEART AND RETURN, AND I WOULD HEAL THEM' (vs. 13-15).
Jesus taught in parables for at least several reasons: (1) to help people learn something they did not know or understand by using a comparison with something from their life that they did understand; (2) to embalm the truth so that when the parable is remembered, the lesson taught is also remembered; (3) to allow people to learn truth without another factor (e.i. pride, fear) keeping them from accepting it. Nathan used a parable for this reason to get David to acknowledge and repent of his sin (2 Samuel 12:1-14).
The question we must ask ourselves...
Is my heart dull?
The upcoming articles are going to be some of the parables Jesus taught. This will be a good opportunity for us to learn spiritual truths from Jesus. However, only those whose heart is prepared and willing to actively pursue understanding will obtain it.
A person with a dull heart may decide they don't have time to read or some other excuse along that line.
A person with a dull heart may read and have trouble understanding and stop their efforts there.
But the person who will surely discover the spiritual truth is the one who is committed to doing whatever it takes to understand and is willing to be a doer of Jesus' teaching. Even if that means acknowledging their error and changing.
There is a reason the prophet Micah (6:8) when revealing what God required of the people included in his response walking "humbly with your God." Humility is necessary for a student to successfully learn and allow teaching to shape their mind and heart and therefore future thoughts, speech, and actions.
Many people want a Savior, but not a Master. God made Jesus both and we must accept Him as our Master if He is going to be our Savior as well. I know this to be true because I read Peter's sermon to the Jews on Pentecost and Peter's culminating point of conviction was the following: "Therefore let all the house of Israel know for certain that God has made Him both Lord and Christ--this Jesus whom you crucified" Acts 2:36.