Sen. Joseph Lieberman has a new book out-“The Gift of Rest,” an aptly titled tome for a longtime politician on the eve of his retirement from the Senate.

But Lieberman’s book isn’t about stopping work, except for one day of the week. It’s a 230-page description and celebration of the Sabbath, even ending with a how-to from the senator for those wanting to start their own Sabbath observances.

But before the next Saturday arrives, the Connecticut independent is gearing up to promote the book at an event in Washington this week. Here’s a tidbit from the promo for the event:

“In an era of limitless connectivity, overscheduling and declining religious observance, fewer and fewer set aside a day of rest,” reads the media advisory for a Tuesday s book launching, to be held at the American Enterprise Institute, a center-right think tank. “Yet, argues former vice presidential candidate and Senator Joe Lieberman, ceasing all activity, including work, for a weekly Sabbath observance has profound benefit for people of all religions.”

In the book, Lieberman describes how observing the Sabbath has enhanced his life, both personal and political. One chapter also describes the times when he decided to break the Sabbath, for example when he took an urgent phone call to try dissuade a colleague from dropping off a climate change bill–to no avail.

It’s unclear how much of a blockbuster the book will be, a Howard Books publication selling for $22 in hardback. But maybe Lieberman will write a more juicy political tell-all after his current term ends in 2012.