The parable of the sower could also be called the parable of the soils. The Holy Spirit tills the soil of hearts to make them ready for the Word of God! 4:12 shows us that without the Holy Spirit to enlighten us, none of us could believe.
John 16:7-11 “But I tell you the truth, it is to your advantage that I am going away. For if I do not go away, the Advocate will not come to you, but if I go, I will send him to you. And when he comes, he will prove the world wrong concerning sin and righteousness and judgment—concerning sin, because they do not believe in me; concerning righteousness, because I am going to the Father and you will see me no longer; and concerning judgment, because the ruler of this world has been condemned.”
For those of us who are believers the parable reminds us of something else. Now that the Spirit has tilled our hearts, are we making sure that our soil remains good? We need to pray, to study, to worship, and to obey if we expect to produce a harvest for God.