Jesus said to the crowds:
“This is how it is with the Kingdom of God;
it is as if a man were to scatter seed on the land
and would sleep and rise night and day
and the seed would sprout and grow,
he knows not how.
Of its own accord the land yields fruit,
first the blade, then the ear, then the full grain in the ear.
And when the grain is ripe, he wields the sickle at once,
for the harvest has come.”
“To what shall we compare the Kingdom of God,
or what parable can we use for it?
It is like a mustard seed that, when it is sown in the ground,
is the smallest of all the seeds on the earth.
But once it is sown, it springs up and becomes the largest of plants
and puts forth large branches,
so that the birds of the sky can dwell in its shade.”
With many such parables
he spoke the word to them as they were able to understand it.
Without parables he did not speak to them,
but to his own disciples he explained everything in private.
4:26–29 These verses recount another seed parable, one that is found only in Mark. This time the focus is on the seed’s intrinsic power to grow of its own accord. The sower liberally scatters his seed, then goes on with the routine of his daily life. Slowly, imperceptibly, the seed begins to sprout. The farmer does not know how this happens; even today, with the tremendous advances in microbiology, life remains a mystery. Nor can the farmer control the process. According to its natural stages the land yields fruit, first the blade, then the ear, then the full grain. The farmer can water, weed, and fertilize the ground as the months go on, but he cannot make the ripe grain appear a day before its appointed time. Farming requires an element of trust and patience. Yet the moment the harvest has arrived, the farmer is ready with his sickle to reap without delay. The harvest is a biblical image for the final judgment (Joel 4:13; Rev 14:14–15).
4:30–32 It is as if Jesus is thinking aloud, searching for ways to help his listeners to grasp the mystery of the kingdom (see 4:11). Because the kingdom is a divine reality, it cannot be defined or contained in human categories. It can be understood only by using analogies, word pictures that force the listener to think and ponder at a deeper level. Once again, the earthly reality most suitable as an analogy to the kingdom is, of all things, a tiny seed. In this third seed parable, the emphasis is on the seed’s smallness. For Jesus’ Jewish audience, the idea of the kingdom as a seed must have been quite a surprise. A more predictable comparison would be a mighty army (see Isa 13:4; Joel 2:11) or a cataclysmic earthquake (Isa 29:6). But no, the kingdom is like a mustard seed, which Jesus describes (using the device of hyperbole, or exaggeration, for effect) as the smallest of all the seeds on the earth. But once sown, it springs up and becomes the largest of plants (another hyperbole).
In mentioning large branches that shelter many birds, Jesus is evoking the Old Testament image of a lofty, shady tree, symbolizing an empire that grants protection to peoples of different races and tongues (Ezek 17:23; 31:6; Dan 4:9). The parable of the mustard seed thus points to the future worldwide reach of the kingdom of God.
4:33 Mark’s final word on the parable discourse is another affirmation that Jesus spoke in parables not to obfuscate (as vv. 11–12 might suggest), but to adapt the mystery of the kingdom to the capacity and openness of his listeners.
4:34 Although Jesus spoke to the crowds only in parables, to his own disciples he explained everything in private. Who are these privileged disciples? Mark 3:32–35; 4:10 make clear: not just the Twelve, called to a special mission, but all “those present along with the Twelve”—that is, all those who choose to be disciples by staying close to Jesus to listen to his teachings, and by doing the will of the Father.
Today’s Gospel Friends, today’s Gospel compares the Kingdom of God to a mustard seed that “when it is sown, it springs up and becomes the largest of plants.” It seems to be a law of the spiritual life that God wants good things to start small and grow over time.
We’re tempted to say, “You’re God. Just get on with it. Do it!” But why would God work the way he does? We might attempt a few explanations. It is a commonplace of the Bible that God rejoices in our cooperation. He wants us to involve us, through freedom, intelligence, and creativity, in what he is doing. And so he plants seeds, and he wants us to cultivate them.
Consider what God said to St. Francis: “Francis, rebuild my Church.” God could have rebuilt his Church without Francis, but he wanted him to get involved. When things start small, they can fly under the radar while they gain strength and heft and seriousness. Also, those involved can be tested and tried. Suppose you want to do something great in the life of the Church and you pray and God gives you massively what you want. You might not be ready, and your project will peter out. So be patient and embrace the small invitations.
– Bishop Robert Barron
May the virtues of faith, hope, and love go with you today – DV.
 Mary Healy, The Gospel of Mark, Catholic Commentary on Sacred Scripture (Grand Rapids, MI: Baker Academic, 2008), 91–92.