This brief explanation is the center of the whole parable. The seed is the word of God (in the previous verses, we had already taken into account that the seed used in the parable is the word of God, knowing beforehand that Jesus explains it that way). This means that the source of spiritual life is not a person’s natural goodness within, but the divine word that comes from outside and falls into a person’s heart. The word has life, power, and fruitfulness, just as the seed does. This verse also teaches us the nature of ministry. The sower is called to sow. A person’s work is the faithful spreading of the word. Growth and fruit are ultimately God’s work, though the responsibility of the human heart remains. This is a comfort to all who serve with the word. They are obligated to sow, but they should not take upon themselves what only God can give: true life and fruit.