Jesus came to confirm the promises to the Jews.
`Now I say that Jesus Christ has become a servant to the circumcision for the truth of God, to confirm the promises made to the fathers,..` (Rom. 15: 8)
Matthew tells us about those promises that God gave to the Father. Jesus confirmed them to the people in parables. In Matthew 13 we read of the kingdom of heaven parables. The disciples asked Jesus why He spoke to the people in parables.
Jesus said, " Therefore I speak to them in parables, because seeing they do not see, and hearing they do not hear nor do understand.` (Matt. 13: 14)
This was a quote from Isaiah. And he said "Go, and tell this people: keep hearing, but do not understand; keep on seeing, but do not perceive." (Isa. 6: 9)
The first parable was of the seed and the sower, which you are referring to. Jesus tells His disciples that -
`When anyone hears the word of the kingdom, and does not understand it, then the wicked one comes and snatches it away etc ` (Matt. 13: 18 - 23
That `word` is the rulership that the prophet Daniel spoke about, the earthly kingdom rule of the God of Heaven, that He would set up His kingdom and it would not pass away.
`And in the days of those kings the God of heaven will set up a kingdom which shall never be destroyed;...` (Dan. 2: 44)
The people had to receive the Word of the Kingdom by faith and obey.
That was a promise to Israel and God will fulfill it to them.
But why speak in parables?
The Purpose of the Parables
10 Then the disciples came and said to him, “Why do you speak to them in parables?”
11 And he answered them,
“To you it has been given to know the secrets of the kingdom of heaven [the Gospel], but to them it has not been given. 12 For to the one who has, more will be given, and he will have an abundance, but from the one who has not, even what he has will be taken away.
13 This is why I speak to them in parables,
because seeing they do not see, and hearing they do not hear, nor do they understand. 14 Indeed, in their case the prophecy of Isaiah is fulfilled that says:
“‘“You will indeed hear but never understand,
and you will indeed see but never perceive.”
15 For this people’s heart has grown dull,
and with their ears they can barely hear,
and their eyes they have closed,
lest they should see with their eyes
and hear with their ears
and understand with their heart
and turn, and I would heal them.’
16 But blessed are your eyes, for they see, and your ears, for they hear.
17 For truly, I say to you, many prophets and righteous people longed to see what you see, and did not see it, and to hear what you hear, and did not hear it.
This explicitly states, though seeing they do not see; hearing they do not hear, nor do they understand. This destroys any synergistic position that insist people can understand or can see or hear! The Word of God comes with power to heal his people and restores the blind to see, the deaf to hear, the darkened mind to understand. It is God who calls us out of the darkness into his marvelous light. Like a command to let there be light!