Read Mark 4:26-34
26 Jesus went on to say, “The Kingdom of God is like this. A man scatters seed in his field. 27He sleeps at night, is up and about during the day, and all the while the seeds are sprouting and growing. Yet he does not know how it happens. 28The soil itself makes the plants grow and bear fruit; first the tender stalk appears, then the ear, and finally the ear full of corn. 29When the corn is ripe, the man starts cutting it with his sickle, because harvest time has come.
30 “What shall we say the Kingdom of God is like?” asked Jesus. “What parable shall we use to explain it? 31It is like this. A man takes a mustard seed, the smallest seed in the world, and plants it in the ground. 32After a while it grows up and becomes the biggest of all plants. It puts out such large branches that the birds come and make their nests in its shade.”
33 Jesus preached his message to the people, using many other parables like these; he told them as much as they could understand. 34He would not speak to them without using parables, but when he was alone with his disciples, he would explain everything to them.
Jesus parables remind us of the great differences small things make. We only hear of the great things people do - and don't hear enough of the little things; small acts of kindness whose sum is greater than the big things people do.