Luke 13:21Meaning & Commentary from the Church Fathers

Or, any man receiving a grain of mustard seed, that is, the word of the Gospel, and sowing it in the garden of his soul, makes it a great tree, so as to bring forth branches, and the birds of the air (that is, they who soar above the earth) rest in the branches, (that is, in sublime contemplation.) For Paul received the instruction of Ananias (Acts 9:17.) as it were a small grain, but planting it in his garden, he brought forth many good doctrines, in which they dwell who have high heavenly thoughts, as Dionysius, Hierotheus, and many others.

Or else; The kingdom of God is the Gospel, through which we gain the power of reigning with Christ. As then the mustard seed is surpassed in size by the seeds of other herbs, yet so increases as to become the shelter of many birds; so also the life-giving doctrine was at first in the possession only of a few, but afterwards spread itself abroad.

Or, the three measures of meal are the race of mankind, which was restored out of the three sons of Noah. The woman who hid the leaven is the wisdom of God.

Let those who are uncertain about these matters consider this: a person who has garnered even a small measure of virtue, despite not having the opportunity to nurture it fully, yet harbored such intentions without being able to act upon them—whether due to negligence, inattention, or lack of fortitude, and continually postponing these intentions—will not be overlooked by the just Judge when they are unexpectedly called to account. In fact, after this individual has departed, God will inspire their neighbors, guiding their thoughts and hearts, and moving their souls, leading them to rush to assist him. Because the Lord has touched their hearts, they will seek to remedy the deficiencies of the departed.

I reflect on the Gospel account of the widow, the humble widow who, in her poverty, was wealthier than all of Israel. By taking a mustard seed and adding leaven to three measures of flour, she embodied the divine mystery of the Father and the Son through the grace of the Holy Spirit. She contributed two small coins to the church's treasury (Luke 21:2), giving all she owned, her entire wealth, as a testament to her faith in the two covenants. Her coins symbolize the two seraphim, who thrice glorify the Holy Trinity and are offered to the church's treasury. In this context, the coal, taken with the tongs of both covenants, serves to purify the lips of sinners (Isaiah 6:6-7).

In another place, a grain of mustard seed is introduced where it is compared to faith. If then the mustard seed is the kingdom of God, and faith is as the grain of mustard seed; faith is truly the kingdom of heaven, which is within us. (Luke 17:21.) A grain of mustard seed is indeed a mean and trifling thing, but as soon as it is crushed, it pours forth its power. And faith at first seems simple, but when it is buffeted by adversity, pours forth the grace of its virtue. The martyrs are grains of mustard seed. They have about them the sweet odour of faith, but it is hidden. Persecution comes; they are smitten by the sword; and to the farthest boundaries of the whole world they have scattered the seeds of their martyrdom.

All the flour has been fully processed. This metaphor, referred to as a parable, is found in the twenty-fourth chapter, so you may seek its meaning there as well. This offers the clearest understanding. The woman symbolizes the Church of God, while the leaven represents the sacred and divinely inspired law. The three aspects of the soul correspond to the three measures: anger, reason, and the aspiration for righteous deeds, within which the divine message is infused to transform the nature of the soul.

Or else, by the leaven our Lord means the Holy Spirit, the Sower proceeding (as it were) from the seed, which is the word of God. But the three measures of meal, signify the knowledge of the Father, and the Son, and the Holy Spirit, which the woman, that is, Divine wisdom, and the Holy Spirit, impart.

Doesn’t this suggest that the mind, recognizing the Lord's word within, has encapsulated it in a threefold existence, as noted by the Apostle: body, spirit, and soul? In its thoughts, it has united all their intricacies, similar to flour that has been scattered, into one cohesive leaven of faith, anticipating that in all things it will reflect the transformative word that operates within it.

Or, by the leaven He speaks of love, which kindles and stirs up the heart; the woman, that is, the Church, hides the leaven of love in three measures, because she bids us love God with all our hearts, all our minds, and all our strength. And this until the whole is leavened, that is, until love moves the whole soul into the perfection of itself, which begins here, but will be completed hereafter.

The Parable of the Leaven In expressing the vision of the Kingdom of God established on earth, Jesus Christ shared the parable of the leaven. He asked, "To what can I compare the kingdom of God? It is like leaven that a woman took and mixed into three measures of flour until the entire batch was leavened." It is understood that a small quantity of leaven, when introduced into a significant amount of dough, influences the entire mixture and sparks fermentation. Likewise, the small community of Christ's followers will bring forth a great Kingdom of God on earth, intended to unite all humanity. “Do not question, ‘What can we twelve do in the midst of such a vast crowd? In this very situation, your strength will be demonstrated; you, who find yourselves among the multitude, will not retreat. Just as leaven permeates the dough through direct contact and integration, you, by forging an unbreakable bond and unity with those who oppose you, will achieve victory over them.”

To illuminate the mysteries of the kingdom of heaven for His disciples, the Saviour shared additional parables that expanded on the central message. In the parable of the sower, He illustrated the process of sowing seed and the varying outcomes depending on the condition of hearts. He then described the transformative potential of the seed within a receptive spirit. The Kingdom of God resembles a mustard seed (Matt. 13:31-32; Mk. 4:30-34), one of the tiniest seeds, which, once planted, grows into a tree larger than all others, providing shelter for the birds of the air. Similarly, it is likened to leaven, which a woman mixes into three measures of flour until the entire batch is leavened.