In this secular age, the idea of a Senator writing what amounts to a guidebook for observing the Sabbath might seem more than a little out of the ordinary.

And, truth be told, it probably is. But Joe Lieberman has never seemed to mind being perceived as standing a bit off the beaten path, so “The Gift of Rest: Rediscovering the Beauty of the Sabbath” is really no stretch for the Connecticut Independent.

“For me, Sabbath observance is a gift because it is one of the deepest, purest pleasures in my life. It is a day of peace, rest, and sensual pleasure,” Lieberman writes. “By sensual I don’t mean sexual — though you might find it interesting to know that one religious ‘responsibility’ given to every married Jew is to make love with their spouse on the Sabbath because this is meant to be a day on which we experience the fullness of life.”

Lieberman returns to the idea of sensuality — and even sexuality — elsewhere, though a peek into the romantic life of a Senator might not be what the reader expects when picking up this book.

Still, those instances fit nicely into the nature of “The Gift of Rest.” It is intensely personal while striving with some success to universalize the experience of observing the Sabbath.

“This is something I’ve been wanting to do for a long time,” Lieberman said in an interview with Roll Call, “because of how much my Sabbath observance has meant to my life.” He said writing the book was among the most important things he’s done.

Everybody, Lieberman said, whether a person of faith or not, can benefit from the time and space that Sabbath observance provides.

“I love the Sabbath and believe it is a gift from God that I want to share with everyone who reads this book, in the hopes that they will grow to love it as much as I do,” Lieberman writes in the author’s note that begins the book.

Politics rarely intrudes, and when it does Lieberman uses it to make a point. He devotes one chapter to those occasions when it is permissible to interrupt the Sabbath. I think the book could have done without it, if for no other reason than because politics is for the most part joyously absent from the rest of the narrative.

(One exception is an experience Lieberman shares from the 2008 campaign trail, in which he counsels GOP vice presidential nominee Sarah Palin using the story of Esther.)

It is in the sections in which Lieberman offers suggestions for how to observe the Sabbath that the book becomes less of a quiet dissertation on practical theology and more of a modern how-to guide, a “Chicken Soup for the Sabbath Deprived.”

“Let yourself take an afternoon nap!” he writes.

“Consider not wearing a watch on the Sabbath. Don’t worry about being late.”

“Read or sing Psalm 23, which offers God’s assurance of His providential protection as we contemplate the coming week.”

As you can see by these suggestions, the book is ecumenical. Christians can nap as well as Jews, and fewer wristwatches would probably serve everybody well.

The book is old-fashioned in the best sense: It reveres the past and is sentimental without devolving into nostalgia. Lieberman employs the lovely archaic language of the King James version of the Bible rather than more modern translations.

And although Lieberman’s book is naturally focused on the practices of the Jewish Sabbath, he never loses connection with the gentile reader, whether he is discussing the Mishnah, Maimonides or Tevye from “Fiddler on the Roof.”

Lieberman tells a number of heartwarming tales about his family, but my favorite story in the book concerns not a relative but a rabbi and a young student (it’s a story a theology professor of mine told to a classroom full of young, doubting students many years ago).

The rabbi and the student are debating whether the world was created by accident or design. After a while the rabbi said he had to leave but invited the student to return later to resume the debate. When the student returned, he saw a beautiful landscape painting of mountains, rivers, flowers, animals and people. When the rabbi came into the room, the student praised the painting and asked who the artist was. There was no artist, the rabbi told him. The house painter accidentally spilled his paints on the canvas covering the floor, and the painting was the result. The student, incredulous, said that was impossible.

A response for which the rabbi was ready: “You find it impossible to believe that this beautiful painting happened by accident, and yet you nevertheless argue that our much more beautiful world was created by accident.”

Far from the loud debates and bustling burdens of the Senate, Lieberman has given us a gift of active contemplation and quiet appreciation.

“The world can get by for a day without me,” Lieberman said.

That might be the most valuable lesson of all.