VATICAN CITY (CNS) -- Feeling sad, disappointed or ashamed of oneself sometimes is normal and even can lead to conversion, but when people wallow in their sadness it becomes a dangerous vice, Pope Francis said.

"We all go through ordeals that generate sorrow in us, because life makes us formulate dreams that are then shattered," the pope said during his weekly general audience Feb. 7. While some people, "after a time of turmoil, rely on hope," others "wallow in melancholy, allowing it to fester in their hearts."

When "sadness is the pleasure of non-pleasure," he said, it goes from being a natural emotion to being "an evil state of mind."

Continuing his series of audience talks on vices and virtues, the pope looked at how nurturing the "type of sorrow that creeps into the soul and prostrates it in a state of despondency" is a denial of the deep-seated hope that faith in God should produce.

Pope Francis said it is like taking a piece of candy that is "bitter, bitter, bitter, without sugar, awful, and sucking on that candy."

The kind of sorrow that leads one to lose hope in God "must be fought resolutely and with every strength, because it comes from the evil one," he said. "It is a devious demon, that sorrow. The fathers of the desert described it as a worm of the heart, which erodes and hollows out its host."

Just a week before Lent was to begin in the Latin-rite church, the pope said that "it is a grace to lament over one's own sins, to remember the state of grace from which we have fallen, to weep because we have lost the purity in which God dreamed of us."

But that sorrow should lead to the joy of knowing that one is forgiven and loved by God, he said.

When one is sad and disappointed, even laid low by the grief of losing a loved one, he said, a Christian holds on to faith in the resurrection of Jesus and the knowledge that all can be saved.

"We must be attentive," the pope said. "Sadness can be a very bad thing that leads us to pessimism, to a self-centeredness that is difficult to heal."