Mark 4:30

And he said, How shall we liken the kingdom of God? or in what parable shall we set it forth? 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, 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.

THE PARABLE OF THE MUSTARD SEED

How shall we liken, ... In this, Jesus employed a device often used by good teachers, seeking to stimulate thinking on the part of his audience.

Less than all seeds ... That certain seeds may be smaller than a mustard seed is no problem. Hyperbolic language was frequently employed then, as throughout history, in order to stress a point. Matthew's "all Judaea" is hyperbole. Compare Matthew 3:5 and Luke 7:30.

Greater than all herbs ... Many commentators stress the great size of the mature mustard tree, which in some parts of the world reaches to a height of more than twenty feet. Bickersteth reported such large specimens "on the slopes of the mountains of Chile that one could ride under the branches."[39] The great point in this short parable is the contrast between the small seed and the mighty growth attained.

The birds of the heaven ... It is illogical to press a parable down upon its all fours, but this writer cannot resist the analogy suggested by the birds. The mustard tree itself is the kingdom of God, beginning small and becoming great; and the fact that birds can build nests even in small trees makes it unlikely that the birds were introduced into this Parable solely to emphasize the size of it. They are a perfect representation of the extraneous and unrelated activities which through the ages have associated themselves with it. Just as the birds could not corrupt the tree, the foul birds whose nests have been built in the kingdom of God cannot corrupt the institution with which they are connected by association only, actually having no identity whatever with it. This interpretation is supported by Matthew 13:4,19, and Revelation 18:2. The person planting the seed does not appear prominently in the parable; but the kingdom of God which was produced by it identifies the sower here with God, or Christ, as in the parable of the sower.

The following analogies are discernible:

The seed is the word of God.

The one who sowed it is Christ

The mustard tree is the kingdom of God.

The earth is the world.

The smallness of the seed is the smallness of the kingdom's beginning.

The greatness of the tree is the vast extent of the kingdom.

The birds are the "operations" which are either evil or at best irrelevant to the kingdom, but which are connected with it, and yet no part of it.

For further thoughts on this parable, see the Commentary on Matthew, pp. 193-194. It has been suggested by some that Jesus' purpose in giving this parable was to offset any pessimism arising from parables like that of the sower and of the tares, wherein unproductive soils and hostile activity of enemies were stressed.