VATICAN CITY, SEPT. 3, 2003 (Zenit.org).- The secret of happiness and optimism lies in doing good for the love of God, says John Paul II.

The Pope delivered this message to the 9,000 pilgrims at today's general audience, dedicated to a meditation on Psalm 91(92), a hymn in praise of God the creator.

Good and evil are repeatedly confronted in this biblical composition, the Holy Father said.

"The conduct of the faithful is dedicated to celebrate the divine works, to penetrate the depth of the Lord's thoughts, and in this way his life radiates light and joy," he said.

On the contrary, in the case of the "perverse man," momentary fortune makes him "arrogant, but in reality he is inwardly fragile and, after ephemeral success, doomed to failure and ruin," the Pope added.

"The conduct of the faithful is dedicated to celebrate the divine works, to penetrate the depth of the Lord's thoughts, and in this way his life radiates light and joy," he said.

Summarizing his meditation, the Pontiff said that "Psalm 91 exudes, therefore, happiness, trust, optimism: gifts which we must ask God for precisely in our time, in which the temptation to lack of trust and even despair easily insinuates itself."

The Holy Father illustrated his message with words from St. Augustine: "Whatever you do, do it with joy. Then you do good and you do it well. If, instead, you act with sadness, even if through it you do good, it is not you who do it."

John Paul II was continuing his series of weekly meditations on the Psalms and Old Testament canticles. Others can be consulted at the ZENIT Web page.