30 And he said, How should we liken the kingdom of God, or with what comparison should we compare it? 31 As to a grain of mustard [seed], which, when it is sown upon the earth, is less than all seeds which are upon the earth, 32 and when it has been sown, mounts up and becomes greater than all herbs, and produces great branches, so that the birds of heaven can roost under its shadow.
33 And with many such parables he spoke the word to them, as they were able to hear, 34 but without a parable spoke he not to them; and in private he explained all things to his disciples.
Matthew Henry's Commentary on Mark 4:30-34
Commentary on Mark 4:21-34
(Read Mark 4:21-34)
These declarations were intended to call the attention of the disciples to the word of Christ. By his thus instructing them, they were made able to instruct others; as candles are lighted, not to be covered, but to be placed on a candlestick, that they may give light to a room. This parable of the good seed, shows the manner in which the kingdom of God makes progress in the world. Let but the word of Christ have the place it ought to have in a soul, and it will show itself in a good conversation. It grows gradually: first the blade; then the ear; after that the full corn in the ear. When it is sprung up, it will go forward. The work of grace in the soul is, at first, but the day of small things; yet it has mighty products even now, while it is in its growth; but what will there be when it is perfected in heaven!