To Jesse Schwartz, a pilgrimage to the woods is a true Jewish day of rest.

For two years, he has been leading small groups to Tuolumne Meadows in Yosemite National Park and other nearby spots to celebrate Shabbat in the wild.

"It's 25 hours of sacred time and sacred space. We give ourselves the gift of Shabbat without interruption from telephones, faxes, computers, letters, bills," says Schwartz, of Kensington.

This month, Schwartz began taking his Shabbat-in-the-wilderness concept a step further. Inspired by Native American practice, he led what he calls a Jewish "vision quest" that lasted a full 48 hours. During daylight hours, participants wandered off alone in different directions for solitary journal writing and meditation. In the evenings, the group convened around a campfire to share the day's thoughts and ideas.

This may not be as traditional as a Saturday morning in synagogue, but Schwartz insists it should be.

"Vision quests in the wilderness go back to the very foundations of Judaism. Abraham, Isaac, Jacob, Moses, Ezekiel — all of them received their inspiration in the desert, in the wilderness. It's as Jewish as can be," says Schwartz.

The menu for this weekend excursion? Juice and water. Food was optional, Schwartz says, but not recommended for full spiritual effect.

"We fast to cleanse, to renew, to gather our energy. If you fast properly, when you come off of it, you experience a surge of life energy. You're ready to tackle the world," he says.

While Schwartz applauds the spiritual benefits of fasting, he makes a career of food as the driving force behind Living Tree Community Foods, which sells organically grown dried fruits and nuts around the world. He also founded the Living Tree Nursery, a grower and distributor of historical and biblical fruit trees.

For this Brooklyn-bred 53-year-old, the road to becoming an organic-fruit-growing, mountaineering, one-with-nature Jew started with a civil engineering degree from the Massachusetts Institute of Technology.

"I left Judaism to go into science," Schwartz explains.

As a professor of economic theory, he taught at institutions all over the world, including Waterloo University in Canada and San Diego State. But after years in academia, he "felt a calling to the land." It was a pull he had first experienced as a child on his grandparents' dairy farm in New Jersey.

He left university life and in 1979 began farming for a living in Bolinas, at which time he began reconnecting with Judaism.

He was a member of Berkeley's Aquarian Minyan for 15 years. The group, he recalls, "was a wonderful gate, a path toward returning to Judaism. They accepted me, no questions asked."

Then after a trip to Israel two years ago, Schwartz's religious journey led him from his renewal synagogue to Berkeley's Orthodox Congregation Beth Israel, where he is currently a member. After years as a secularist, he now describes himself as observant.

"Shabbat has become a necessity for me," says Schwartz, who planned his first outdoor vision quest to coincide with the Jewish period of mourning for the destruction of the First and Second Temples.