The Lord often spoke in parables. There are two reasons for this. The first is to liken the kingdom of heaven to things we on earth can relate to and understand (John 3:10-12). Jesus said this at the start of many of His parables. The other reason is that those who rejected Him were always trying to twist what He said and use it against Him. He spoke in parables because they had closed their eyes and ears anyway (Matthew 13:9-17, John 8:43). He wanted them to hear and believe, but they refused. So to them His words were just parables, although sometimes they knew exactly what He meant and still rejected it (Matthew 21:45, John 8:59, John 10:30-33). The insincere and unbelieving will never properly receive the word of God, and that is what one of His key parables is about - the parable of the sower (Matthew 13:3-9 & 18-23). In Mark's account of this parable, Jesus said, "Know ye not this parable? and how then will ye know all parables (Mark 4:9)?"
In the days of the Bible, people were much more directly connected to food production than most westerners are today. They understood the importance of properly tending the ground, placing the seed, and harvesting. However, in this story a man seems to be irresponsibly throwing his seed anywhere. He did not have a particular field, and he did not prepare the ground at all. He knew the condition of the ground, and did not seem to care. There were four conditions of soil the seed fell into. The first was the wayside. They did not have paved sidewalks. The wayside was the ground that the pedestrian traffic traveled over. It was packed down hard, so the seed could not get in deeply. The birds ate it. The second was stony ground. The seed could not sink deep roots, so it withered in the hot sun. The third was thorny ground, and the seed was choked by the weeds. Then there was good ground that produced fruit.
The disciples asked what this meant. Jesus said the seed is the word of God, and the ground is the condition of men's hearts when they hear the word. Some people's hearts are hard in unbelief, so the word does not get in. The devil comes and takes it away before it can benefit their souls. Some people hearts have stones in them. The word gets in, but cannot go deep. When the heat is on, they walk away from God. Others are so focused on the material things of this life that they do not give the word of God its proper priority, so it does not produce in them either. Then there is the heart that is in the right condition to receive the word of God and have it produce fruit in and through them. The problem is not with the word of God. It can always do what it is supposed to. "So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it (Isaiah 55:11)." The problem is the condition of the ground - our hearts.
The good news is that the sower (Jesus Christ) is not irresponsible with the seed. He is giving everyone an opportunity to be saved. If our hearts are not in the right condition, they can be. If our hearts are hard, we can choose to break up the hardness of unbelief (Psalm 34:18, Psalm 51:17, Jeremiah 4:3-4, Hosea 10:12, Hebrews 3:7-19) If our hearts are stony, God will remove the stones if we ask Him to (2Kings 22:19, Ezekiel 11:19, Ezekiel 18:31, Ezekiel 36:25-27). If we have the thorns of earthly cares, we can put our trust in God and cast our cares upon Him so we can focus on the eternal things (Deuteronomy 10:16, Deuteronomy 30:6, Jeremiah 4:4, Colossians 2:11 - circumcise heart (Gen 17:10-14), Jeremiah 4:3, Matthew 6:19-34,1Timothy 6:6-19, 1Peter 5:7).
God created all things good, and to be fruitful (Genesis 1:28, John 15:1-8). The curse came because of sin, but Jesus took the curse on Himself for us (Galatians 3:13). They placed a crown of thorns on His head (Matthew 27:29). He means for us to live a spiritually abundant life (John 10:10). It is the devil that wants us to be barren and unfulfilled. Your potential can only be fulfilled in the Lord Jesus Christ (Matthew 16:25, John 14:6, Colossians 3:3-4).