30 And he said, How shall we liken the kingdom of God? or in what parable shall we set it forth? 31 It is like a grain of mustard seed, which, when it is sown upon the earth, though it be less than all the seeds that are upon the earth, 32 yet when it is sown, groweth up, and becometh greater than all the herbs, and putteth out great branches; so that the birds of the heaven can lodge under the shadow thereof.
33 And with many such parables spake he the word unto them, as they were able to hear it; 34 and without a parable spake he not unto them: but privately to his own disciples he expounded all things.
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!