Then Jesus said, "This is what God’s kingdom is like. It’s as though someone scatters seed on the ground, then sleeps and wakes night and day. The seed sprouts and grows, but the farmer doesn’t know how. The earth produces crops all by itself, first the stalk, then the head, then the full head of grain. Whenever the crop is ready, the farmer goes out to cut the grain because it’s harvesttime."
He continued, "What’s a good image for God’s kingdom? What parable can I use to explain it? Consider a mustard seed. When scattered on the ground, it’s the smallest of all the seeds on the earth; but when it’s planted, it grows and becomes the largest of all vegetable plants. It produces such large branches that the birds in the sky are able to nest in its shade."
With many such parables he continued to give them the word, as much as they were able to hear. He spoke to them only in parables, then explained everything to his disciples when he was alone with them.