For the earth bringeth forth fruit {i} of herself; first the blade, then the ear, after that the full corn in the ear.

(i) By a certain power which moves itself.

People's New Testament

4:28 First the blade. There is a law of orderly development in natural growth, so also is it in reference to spiritual growth. Compare 1Jo 2:12-14. Some growths are quicker than others, but in all there is growth. And we have no right to look for the end at the beginning, the ripened Christian experience in the young convert, the full corn in the first appearance of the blade. Observe, too, that we can know that there is growth by its results, though we know not how, and that each stage of the growth is more apparent than the preceding stage.

Jamieson-Fausset-Brown Bible Commentary

28. For the earth bringeth forth fruit of herself; first the blade, then the ear, after that the full corn in the ear-beautiful allusion to the succession of similar stages, though not definitely marked periods, in the Christian life, and generally in the kingdom of God.

Matthew Henry's Concise Commentary

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!