The Parable of the Mustard Seed (Matthew 13:31–32; Mark 4:30–32; Luke 13:18–19)

The texts below are quoted verbatim from public-domain English translations; nothing is paraphrased.

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St. John Chrysostom (c. 347–407)

Homilies on the Gospel of Matthew, Homily 46 (on Matthew 13:31–32) Source: trans. in the Nicene and Post-Nicene Fathers, First Series, Vol. 10. Public domain. Full text: https://www.newadvent.org/fathers/200146.htm

On why this parable follows those of the sower and the tares, reassuring the disciples who had heard how much of the seed is lost:

The Kingdom of Heaven is like to a grain of mustard seed. That is, since He had said, that of the crop three parts are lost, and but one saved, and in the very part again which is saved so great damage ensues; lest they should say, And who, and how many will be the faithful? this fear again He removes, by the parable of the mustard seed leading them on to belief, and signifying that in any case the gospel shall be spread abroad.

On the smallest seed becoming the greatest herb, an image of the weak disciples whose preaching filled the world:

Therefore He brought forward the similitude of this herb, which has a very strong resemblance to the subject in hand; Which indeed is the least, He says, of all seeds, but when it is grown, it is the greatest among herbs, and becomes a tree, so that the birds of the air come and lodge in the branches thereof. Thus He meant to set forth the most decisive sign of its greatness. Even so then shall it be with respect to the gospel too, says He. Yea, for His disciples were weakest of all, and least of all; but nevertheless, because of the great power that was in them, it has been unfolded in every part of the world.

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St. Cyril of Alexandria (c. 376–444)

Commentary on the Gospel of St. Luke, on Luke 13:18–19 Source: trans. R. Payne Smith, 1859. Public domain. Full text: https://www.tertullian.org/fathers/cyril_on_luke_09_sermons_89_98.htm

On why the parable names the Gospel's preaching "the kingdom of heaven":

The comparison is an excellent one, and most fit to set before them what took place and happened at the divine and sacred preaching of the Gospel, to which He here gives the name of the kingdom of heaven; because it is through it that we gain the right of sharing Christ's kingdom.

On the small beginnings in Judaea and the spread to all nations:

At first then it was addressed to few persons, and within a narrow range, but afterwards it widened its influence, and spread abroad unto all nations. For at first it was spoken in Judaea only, where also the blessed disciples were very few in number: but when Israel disobeyed, the commandment was given to the holy apostles, "having gone to make disciples of all the nations, &c."

On the mustard seed itself, and the humble sparrows who shelter in it:

As therefore a grain of mustard seed is far inferior in size to the seeds of other plants, but shoots up to a great height, far beyond what is usual among herbs, so as for it even to become the lodging of many sparrows, so also the kingdom of heaven, even the new and sacred preaching of salvation, by which we are guided into every good work, and learn Him Who both by nature and verily is God, being at first addressed to but few persons, and as it were small and limited, shot up afterwards into rapid growth, and became the refuge of those who fled to it for shelter, and who may be compared to sparrows, because human things are but of small measure in comparison with God.

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St. Jerome (c. 347–420)

Commentary on Matthew (on Matthew 13:31–32) Source: as preserved in the Catena Aurea of Thomas Aquinas, trans. J. H. Newman, 1841. Public domain.

On the contrast between the dogmas of the philosophers, which wither, and the gospel, which grows into a sheltering tree:

For the dogmas of Philosophers when they have grown up, show nothing of life or strength, but watery and insipid they grow into grasses and other greens, which quickly dry up and wither away. But the Gospel preaching; though it seem small in its beginning, when sown in the mind of the hearer, or upon the world, comes up not a garden herb, but a tree, so that the birds of the air (which we must suppose to be either the souls of believers or the Powers of God set free from slavery) come and abide in its branches.

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St. Hilary of Poitiers (c. 310–367)

As preserved in the Catena Aurea on Matthew. Public domain.

On Christ Himself as the mustard seed, sharp to the taste and least of all, whose strength is drawn out by bruising:

The Lord compares Himself to a grain of mustard seed, ... sharp to the taste, and the least of all seeds, whose strength is extracted by bruising.

On the seed sown in the field as Christ seized, slain, and buried, who rose to surpass all the glory of the Prophets:

This grain then when sown in the field, that is, when seized by the people and delivered to death, and as it were buried in the ground by a sowing of the body, grew up beyond the size of all herbs, and exceeded all the glory of the Prophets.

On the birds of the air as the Apostles, in whose branches the Gentiles find rest from the spirits of the Devil:

By which we understand the Apostles, who put forth of Christ's might, and overshadowing the world with their boughs, are a tree to which the Gentiles flee in hope of life, and having been long tossed by the winds, that is by the spirits of the Devil, may have rest in its branches.

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Blessed Augustine (of Hippo) (354–430)

Questions on the Gospels (Quaestiones in Evangelium) As preserved in the Catena Aurea on Matthew. Public domain.

On the mustard seed as a figure of the warmth of faith and its power against poison:

A grain of mustard seed may allude to the warmth of faith, ... or to its property as antidote to poison.

On the meaning of "dogmas" as the fixed decisions of the sects:

Dogmas are the decisions of sects ... the points, that is, that they have determined.

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St. Gregory the Great (c. 540–604)

Morals on the Book of Job (Moralia in Job) As preserved in the Catena Aurea on Matthew. Public domain.

On Christ as the mustard seed planted in the garden of the sepulchre, a grain in death and a tree in His rising:

Christ Himself is the grain of mustard seed, who, planted in the garden of the sepulchre, grew up a great tree; He was a grain of seed when He died, and a tree when He rose again; a grain of seed in the humiliation of the flesh, a tree in the power of His majesty.

On the birds lodging in its branches as holy souls who rise on the wings of the virtues:

"The birds lodge in its branches," when holy souls that raise themselves aloft from thoughts of earth on the wings of the virtues, breathe again from the troubles of this life in their words and comfortings.