On Sunday Pope Francis compared the action of grace to the growth of seeds planted in a garden, saying God often works in ways that are both unknown and surprising, but which always bring fruit, and because of this it is important to always trust and never lose faith.

In his June 17 Angelus address, the pope noted that if one looks back at history, it can seem like the world is going "in an opposite direction to the design of the heavenly Father, who wants justice, brotherhood and peace for all of his children."

Catholics, he said, are invited to live these periods "as seasons of trial, hope and of vigilant waiting for the harvest."

Pointing to the parable of the seeds in the day's Gospel reading from Mark, Francis explained that both in the past and today, the Kingdom of God "grows in the world in a mysterious and surprising way, awakening the hidden power of the small seed and its victorious vitality."

"Inside the wounds of personal and social events which at times seem to mark the shipwreck of hope, we must remain confident and in the subdued but powerful action of God," he said.

Because of this, when moments of darkness and difficulty come along, "we must not break down, but remain anchored to the fidelity of God and to his presence, which always saves...Remember this: God always saves, he's the savior.."

Pope Francis spoke to pilgrims present in St. Peter's Square during his Sunday Angelus address, in which he focused on the two parables Jesus told his disciples in the day's Gospel reading, the first being about a seed which is scattered and grows of its own accord, culminating with the gathering of the harvest.

The second parable is about the mustard seed, which is the smallest seed but which grows to be one of the biggest shrubs.

In the first parable, the message conveyed is that through Jesus' preaching and action," the Kingdom of God is announced, he made it burst into the field of the world and, like the seed, it grows and develops on its own, with its own strength and according to criteria that are not humanly understandable."

This growth and sprouting inside history, he said, is not dependent on the work of man, but is "expressed by the power and goodness of God."

On the parable of the mustard seed, Francis noted how the small seed grows to become one of the biggest plants in the garden, which is "an unpredictable, surprising growth."

"It's not easy for us to enter into this logic of the unpredictability of God and to accept it in our lives," he said, explaining that Lord encourages each person to have "an attitude of faith which overcomes our own projects, our calculations, our provisions."

This is an invitation to open oneself with greater generosity to God's plan on both a personal and community level, Francis said, adding that every community must pay special attention to "the small and the great opportunities for goodness that the Lord offers to us, allowing  us to be involved in his dynamics of love, of welcome, and of mercy toward all."

The authenticity of the Church's mission, he said, is not measured "by success or the gratification of results, but by going forward with the courage of trust and the humility of abandonment to God."

"It's the knowledge of being small and weak instruments, which in the hands of God and with his grace can fulfill great works, advancing his Kingdom, which is justice, peace and joy in the Holy Spirit," he said, and prayed that Mary would help Catholics to be attentive to God and to collaborate in helping the Kingdom of God grow "in hearts and in history."

After leading pilgrims in the traditional Marian prayer, Pope Francis offered prayers for Yemen, as fighting continues to escalate near the port city of Hudaydah. If the port closes, desperately needed food and other aid would be cut off from thousands of people who already face starvation in the country, increasing the already dire humanitarian situation.

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Francis appealed to the international community on behalf of Yemen, asking that they bring conscience "to the table of discussions in order to avoid a worsening of the already tragic humanitarian situation." He then led pilgrims in praying a Hail Mary.

He then kicked off the "Global Action Week," which is part of the Share the Journey initiative of the papal charity organization Caritas International, urging governments to adopt the global U.N. compacts on migrants and refugees in order to "reach an agreement to ensure the assistance and protection of whoever is forced to leave their own home."