
Way back, people knew that whatever other plans they'd made, they couldn't influence the weather. You could plant your crop as vigorously as you wanted, but for goodness' sake, you had very little control over whether or not the crops actually grew. That was up to God. Knowing how reliant they were on God for good weather, for an abundance of crops, they understood how important it was to celebrate days like Pentecost, the harvest festival.
Perhaps that's why Jesus used the illustration that he did. Think for a moment of his parable of the sower of the seed, and how that went.
On the same day Jesus went out of the house and sat by the sea. 2 And great multitudes were gathered to Him, so that He got into a boat and sat down; and the whole multitude stood on the shore.
3 Then He spoke many things to them in parables, saying: “Behold, a sower went out to sow. 4 And as he sowed, some seed fell by the wayside; and the birds came and devoured them. 5 Some fell on stony places, where they did not have much earth; they immediately sprang up because they had no depth of earth. 6 But when the sun was up they were scorched, and because they had no root they withered away. 7 And some fell among thorns, and the thorns sprang up and choked them. 8 But others fell on good ground and yielded a crop, some a hundredfold, some sixty, some thirty. 9 He who has ears to hear, let him hear.”
-Matthew 13:1-9
Jesus told this parable for a reason. He told this parable because people understood that the harvest, the crops, were important. They understood that there were seeds that were scattered, and some would grow, and others not. And Jesus is informing them that there will be growth, there will be an increase, there will be a harvest. Which seeds will grow?
Jesus says this, knowing that the people should get it. But they will resist. Who are those who hear the word and understand it? Maybe not the people who thought they would. The people listening, did they see themselves as the ones who were growing amongst thorns? Did they see themselves as those growing up and getting snatched by birds? Probably not. But when the time comes for the Holy Spirit to come, who does it come to? It comes to those who will hear it and understand it. That's the whole point of Pentecost, that people can hear God's word for them, maybe for the first time. And hearing, they can understand it.
This is the harvest of the parable writ large. The word of God actually being scattered far and wide, to all sorts of people. You see the word of God being sown abroad, and you get to see the reaction that the people have to the word being preached. Some mock, some are befuddled and confused, and others, well, others hear the word, and respond to it joyfully. And as the disciples go on their way, as Pentecost people, that harvest continues, the harvest of the last of the grain to ripen. The harvest of the final flowers. The gentiles, those who were hungry for God and his word. That is who the harvest is now.
He who has ears, let him hear.