How often in life have you felt the need for somebody to give you a hand, and at the same time realized that no person is able to remedy your situation! It is then that you unconsciously turn to Someone who can make the impossible possible. This Someone has a name: He is Jesus.
Listen to what he tells you:

«Were your faith the size of a mustard seed, you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you.»

Obviously, this image is not to be taken literally. Jesus did not promise his disciples the power to perform spectacular miracles simply to amaze the crowds. To uproot and plant in the sea is a hyperbole, that is a rhetorical exaggeration, intended to instill into the minds of the disciples the fact that with faith nothing is impossible.
The purpose of every miracle that Jesus worked, directly or through his followers, was always to further the kingdom of God or the Gospel, or the salvation of humanity. Uprooting the mulberry tree would not serve this purpose.
The comparison with the “mustard seed” is used to show that what Jesus requires of you is not a great amount of faith, but an authentic faith. The characteristic of an authentic faith is that it is rooted solely in God and not on one’s own strength. If you are assailed by doubts or reservations about your faith, then that means that your faith in God is not yet authentic. It means that you have a faith which is feeble and somewhat ineffective, which is still anchored upon human strength and human logic.
The one who trusts entirely in God lets God himself act and… to him nothing is impossible.
The faith that Jesus wants from his disciples is a totally trusting attitude which enables God to manifest his power. And this faith is not reserved for certain exceptional people. It is possible and dutiful for all believers.

«Were your faith the size of a mustard seed, you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you.»

It is traditionally held that Jesus said these words to his disciples when he was about to send them out on their mission.
It is easy to get discouraged and frightened when you know that you are a small, unprepared flock, with no particular talents, faced with a great crowd of people to whom you must carry the truth of the Gospel. It is easy to lose heart because you realize that you are facing people whose interests are entirely different from the kingdom of God.
It seems an impossible task.
It is then that Jesus assures his disciples that by faith they will “uproot” the indifference and apathy of the world. If they have faith nothing will be impossible for them.
Furthermore, this expression can be applied to all circumstances of life, as long as these serve the progress of the Gospel and the salvation of people.
At times, when we are confronted with insurmountable difficulties, we might even be tempted not to turn to God. Human logic says to us, ‘Give up; it’s no use anyway.’
It is then that Jesus exhorts us not to be discouraged, but to turn to God with trust. In one way or another he will answer us.
That was what happened to Lella. Some months had passed since the day when, full of hope, she first reported to her new job in another country. But now a sense of dismay and loneliness have taken hold of her heart. It seemed as though between her and the girls with whom she lived and worked there was an insurmountable barrier. She felt isolated and estranged among those people whom she wanted only to serve with love. It was all because she had to speak a language which was neither hers nor those to whom she was speaking with.
They had told her that everybody spoke French and she learned it. But coming in direct contact with those people she realized that they studied French only in school and generally spoke it unwillingly.
Many times she tried to “uproot” this segregation that kept her apart from the others, but in vain. What could she do for them?
She could still see in front of her the face of her companion Marie, full of sadness. That evening Marie went up to her room without touching her supper. Lella tried to follow her, but she stopped in front of her door, timid and scared. She would have wanted to knock… but what words should she use to make herself understood? She remained there for a few seconds, then she gave up.
Next morning she went to church and stayed at the back behind the last pews, her face in her hands so that no one would notice her tears. It was the only place where no other language needed to be spoken, where no explanations were required, because there, was Someone who understood beyond words. It was the certainty of being understood that gave her courage and, her soul in anguish, she asked Jesus: “Why can I not share the cross of the other girls and tell them what you yourself had made me understand when I found you: that every suffering is love?”
There she was in front of the tabernacle, almost expecting an answer from him who had brought light into every darkness of her life. She turned her eyes to the Gospel of the day and read: “Trust – have faith – I have conquered the world” (cf. Jn. 16:33). These words were like balsam on Lella’s soul, and she felt a great peace.
When she went back for breakfast, she met Agnes, the girl who took care of the house-cleaning. She greeted Agnes and followed her into the storeroom; then, without a word she started to help her prepare breakfast.
The first one to come down from the rooms was Marie. She came to the kitchen for a cup of coffee, quite in a hurry to avoid seeing anyone. But there, she stopped; Lella’s peace had touched her soul in a manner which was stronger than any word.
That evening, on the way home, Marie pedaled her bicycle beside Lella’s, and trying to speak in a way Lella would understand, she whispered, “Your words are not necessary; today your life said to me: “Start loving, you too!”
Faith had won.

«Were your faith the size of a mustard seed, you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you.»

Chiara Lubich