There is no clinical description possible; that’s the whole point of this passage. If you choose to invest your awareness into your convictions, you become sensitive to what those convictions have to say. In that sense, you are breathing life into them. They become important to you, taking up a strong position in your awareness. Because we lack a cultural basis for this, it is very difficult to do. The Bible refers to the heart as the seat of our convictions. We have a false imagine in its place, of the heart as merely a repository of sentiment.
For the people in Jesus’ day, there was a cultural background for understanding this, but a couple of centuries during which it was pushed aside, even as the terminology persisted. The heart was the symbol for the part of you where convictions reside, where faith can discern God’s will for you. The problem for Jesus’ audience was not like ours — a complete absence of the heart as a separate faculty — but it was more a problem with insensitivity of the heart. We need to destroy our false image and build the entire reference from scratch; they needed to renew the one they already had.
Thus, the Parable of the Sower addresses the different ways the heart can become hardened. In the first instance, the issue was hardness due to the sheer volume of exposure to conventional worldly concerns. This represents someone who is entirely consumed with pragmatism and efficiency, of conforming to norms. The Word of moral truth is too quickly brushed aside because it’s dropped into some preexisting mental category. It’s not received as a fresh calling from the Lord; it’s dismissed as something already dealt with. “We have this under control already.”
In the second instance, the heart is hardened by shallowness. This is someone who has no clue who he is, always looking for the next new thing to entertain and fill the void. Thus, a fresh Word from God is seized as just another fashion of the moment. It is seized fully, but there’s no space to take root. It withers and dies like everything else in this person’s life, and is pushed aside by the next new obsession. A little taste of the tribulation that always comes from obeying God and resisting the world, and it’s over.
In the final instance, the issue is compromise. This heart is already owned by some other deity, and there is no room for Jehovah. The Word is okay until there’s a conflict with previous commitments — and there’s always a conflict. This is the moral adulterer who simply cannot stop sinning, driven as they are like an addict who can’t break the bad habits.
But the Lord always reserves a few open souls for Himself. These are people who receive His Word and are ready to make the next level of commitment. Their fresh convictions eventually bear fruit in more fresh revelations from God (more seeds). This is what Jesus meant by saying those who have a receptive heart will receive even more. Those who are not receptive will become even more alienated. The Word of God polarizes humanity.
Thus, Jesus doesn’t hesitate to break it down for His disciples. Their hearts are sensitive to the Word of revelation. Simplifying it will bear more fruit. All He’s doing is refreshing their Hebrew cultural orientation to think in parables. But notice that the unexplained parable still had the power to draw; it was intriguing. Something inside of them wanted to chase this down because it signaled deep importance. This was no mere curiosity of mind, but a sense of calling. Without that, parables mean nothing, as they did to most Jews of that day.