Today, through two parables, the liturgical readings reveal to us one of the defining characteristics of the Kingdom of God: it is something that grows slowly—like a mustard seed—but eventually becomes so large that it provides shelter for the birds of the air. As Tertullian declared: "We are but of yesterday, and we have filled every place." Through this parable, Our Lord calls for patience, fortitude, and hope. These virtues are especially necessary for those dedicated to spreading the Kingdom of God. One must know how to wait for the sown seed—with God’s grace and human cooperation—to grow, sinking its roots into good soil and rising little by little until it becomes a tree. First and foremost, we must have faith in the potential—the fruitfulness—contained in the seed of the Kingdom of God. That seed is the Word; it is also the Eucharist, sown within us through Holy Communion. Our Lord Jesus Christ likened Himself to the "grain of wheat [that] falls to the ground and dies... [and] produces much fruit" (Jn 12:24).

The Kingdom of God, Our Lord continues, “is like yeast that a woman took and mixed in with three measures of wheat flour until the whole batch of dough was leavened" (Lk 13:21). Here, too, the focus is on the ability of yeast to leaven the whole dough. This is the case with “the remnant of Israel” mentioned in the Old Testament: the “remnant” will save and leaven the entire people. To continue with the parable: the yeast simply needs to be within the dough—to reach the people—acting like salt that preserves against corruption and seasons the entire meal (cf. Mt 5:13). Time must also be allowed for the yeast to do its work.

These parables encourage patience and steadfast hope. They refer to the Kingdom of God and the Church, and they also apply to the growth of this same Kingdom within each of us.