And he said, So is the kingdom of God, as if a man should cast seed into the ground; And should sleep, and rise night and day, and the seed should spring and grow up, he knoweth not how. For the earth bringeth forth fruit of herself; first the blade, then the ear, after that the full corn in the ear. But when the fruit is brought forth, immediately he putteth in the sickle, because the harvest is come.Mark 4:26-29
As we have seen before, parables are not the same as allegories. Not every detail in the parable story represents something else in the lesson or the real world. Jesus does not offer an explanation to us for this parable so we must be careful not to over-spiritualize the characters in the story and miss the main point. Having said that, I think it is important to understand who the man is in this parable.
Commentators have differing opinions of who this man is. Some even speculate that it refers to Jesus. However, we will see in the description of the man that it cannot be Christ.
First of all, it says that this man sleeps. Jesus is God, and, as God, never sleeps nor slumbers (Psalm 121:4).
The next description of the man is that he does not know how the seed grows into a plant. Whether we are talking about natural seed or spiritual seed, this cannot pertain to Christ because the wisdom and understanding of God is infinite (Psalm 147:5).
The last description may have application to Jesus since He will usher in the resurrection, but the first two descriptors show this must be talking about someone other than Jesus.
The man in this parable is the faithful preacher of the word of God. He does his job and “preaches the word.” God is the only One who can bring the new birth, and He is the only One who blesses the preached word to be received by faith. Therefore, the preacher may “sleep” or not fret over these details because it is God Who gives the increase (1st Corinthians 3:6).
The overall lesson in this parable fits very well with the Parable of the Sower. The preacher is to just do his job and preach the gospel faithfully and fully. The reactions are out of his hands so he need not worry about those things. In the end, he, another preacher, or other children of God will see the results of the word of God working in someone and reap the harvest by giving God glory for their discipleship.