Matthew 13:31,32

Ver 3l. Another parable put he forth unto them, saying, "The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field: 32, Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof."

Chrys.: Seeing the Lord had said above that three parts of the seed perish, and one only is preserved, and of that one part there is much loss by reason of the tares that are sown upon it; that none might say, Who then and how many shall they be that believe; He removes this cause of fear by the parable of the mustard seed.

Therefore it is said, "Another parable put he forth unto them, saying, The kingdom of heaven is like unto a grain of mustard seed."

Jerome: The kingdom of heaven is the preaching of the Gospel, and the knowledge of the Scriptures which leads to life, concerning which it is said to the Jews, "The kingdom of God shall be taken from you." [Matthew 21:43] It is the kingdom of heaven thus understood which is likened to a grain of mustard seed.

Aug., Quaest in Ev., i, 11: A grain of mustard seed may allude to the warmth of faith, or to its property as antidote to poison. It follows; "Which a man took and sowed in his field."

Jerome: The man who sows is by most understood to be the Saviour, who sows the seed in the minds of believers; by others the man himself who sows in his field, that is, in his own heart. Who indeed is he that soweth, but our own mind and understanding, which receiving the grain of preaching, and nurturing it by the dew of faith, makes it to spring up in the field of our own breast?

"Which is the least of all seeds." The Gospel preaching is the least of all the systems of the schools; at first view it has not even the appearance of truth, announcing a man as God, God put to death, and proclaiming the offence of the cross. Compare this teaching with the dogmas of the Philosophers, with their books, the splendour of their eloquence, the polish of their style, and you will see how the seed of the Gospel is the least of all seeds.

Chrys.: Or; The seed of the Gospel is the least of seeds, because the disciples were weaker than the whole of mankind; yet forasmuch as there was great might in them, their preaching spread throughout the whole world.

And therefore it follows, "But when it is grown it is the greatest among herbs," that is among dogmas.

Aug.: Dogmas are the decisions of sects [margin note: placita sectarum], the points, that is, that they have determined.

Jerome: For the dogmas of Philosophers when they have grown up, shew 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. The branches of the Gospel tree which have grown of the grain of mustard seed, I suppose to signify the various dogmas in which each of the birds (as explained above) takes his rest. [margin note: Psalms 55:6]

Let us then take the wings of the dove, that flying aloft we may dwell in the branches of this tree, and may make ourselves nests of doctrines, and soaring above earthly things may hasten towards heavenly.

Hilary: Or; 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.

Greg., Mor., xix, 1: 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.

Hilary: 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. For the preaching of the Prophets was allowed as it were herbs to a sick man; but now the birds of the air lodge in the branches of the tree. 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.

Greg.: "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.