VATICAN CITY — Trust is needed on life's journey, Pope Francis said.

Even if life often is marked by "pain, uncertainty and moments of crisis, it is a story of salvation," he said in the preface of a new book.

People of faith know that "in Jesus our every exile ends, and every tear is dried in the mystery of his cross, of death transformed into life like the grain of wheat that breaks apart in the soil" and grows, he said.

The pope's comments appear in a new book by Italian psychologist and family counselor, Salvo Noe; in 2017 Pope Francis had posted on the door of his study a sign Noe had given him, which read, "No complaining" and "Offenders are subject to a syndrome of victimhood that dampens your mood and ability to solve problems."

The new book, titled "The Power of Trust: Ten Steps for Conquering Fear and Developing Self-Esteem," was published in Italian by the St. Paul publishing house in early November.

In the preface, Pope Francis wrote that God's love and faithfulness are what give people the strength to keep going on life's journey and to venture forth on new paths.

"On the journey of life, trust is needed," he said.

It is like farming, he said, where human effort is required, but that act of sowing seeds also requires hope, trust and a period of "powerless waiting" for an unknown outcome. Whether harvests yield much fruit or fail, the farmer still sows those seeds year after year, he said.

Every day, people wake up to start their journey, trusting in the Lord, being open to his surprises, which are "often good, sometimes bad," but Christians always should be confident that, no matter what, God is leading the way to a safe refuge, the promised land.

 Prayer can help people situate themselves in this terrain or "land of faith," where, despite the darkness, difficulties and sorrows, they can be confident that "the light of Christ truly will give us the great harvest in the end," the pope wrote.

"Therefore, we have to learn this even in the darkest nights: to not forget that light is there, that God is already in our life and that we can sow with great faith that God's 'yes' is stronger than all of us."

Gratitude for encountering Jesus turns into hope, he wrote, because it is "precisely the suffering of sowing" that marks the start of a new life and true joy.

"Trust generates love and none of us can live without love, and believing that love should be earned is a horrible slavery," he said, noting how many people seek the spotlight "only to fill an emptiness inside" and are in constant need of validation.

He asked if people could "imagine a world where everyone begs for reasons to get other people's attention and instead no one is willing to freely love another person?"

The new book by Noe, he said, seeks to offer people ample reflection on how qualities like trust "can help us live a better life."