As Jesus’ popularity grows, he has to take care with the crowds since they could easily try to fit him into their expectations and ideas rather than listen to his teaching about God’s will. So Jesus uses parables to find out who is really listening. Then in private, with those he already trusts, he explains the parables. The first one he runs through is about sowing seeds and it describes the range of people who listen to him. If the disciples grasp the meaning, then they’ll understand why Jesus has adopted the parable approach – he has to distinguish true disciples from temporary ones. They’ll then understand better, and reach better to, the responses they will meet when they preach the gospel.
And here is a short talk based on the same passage: He Changed The World (Episode 10)