"As people who love what we do, we can find in our love for this universe a foretaste of that divine love which, in contemplating his creation, declared that it was good," he said June 14.

The Pope spoke to dozens of young astronomy students who were taking part in a monthlong summer school sponsored by the Vatican Observatory.

The summer program in astrophysics, held every two years, accepts a small group of promising university and graduate students, mostly from developing nations, who are specializing in astronomical sciences.

During a private audience in the apostolic palace, the Pope praised the way the study program brings together people from so many different countries, cultures and areas of specialization.

This endeavor shows how "diversity can be united by a common goal of study" and how success in that work depends precisely on this diversity, he said.

"Whether as scientists or believers, it is always important to start by admitting there is much that we do not know. But it is equally important" to never be satisfied with sticking with a "complacent agnosticism," the Pope said.

"Just as we should never think we know everything, we should never be afraid of trying to learn more," he said.

Harmony between scientific knowledge, metaphysics and faith "leads us to understanding, and understanding -- we hope -- will make us open to wisdom," he added.

As humans, "we are more than just thinking, rational beings," he said. "We are also people with a sense of curiosity that drives us to know more; we are creatures who work to learn and share what we have learned for the pure joy of doing so."

In "Paradiso" by Dante Alighieri, the 14th-century Italian poet wrote that it is "love that moves the sun and other stars," the Pope said.

"May your work likewise be 'moved' by love: love for truth; love for the universe itself; and love for one another as you work together amid your diversity."