Few people’s earliest memory of Shabbat will have been quite the same as Susan Pashman’s, who underwent a passage through darkness to light. When she was four, her grandmother in the Bronx would put her in a dumbwaiter on a Friday night and then whisk her up the shaft two floors to her aunt, who had married a more religious man.

She ought to have been frightened as she was hauled up the “black tunnel” with the “moldy stench” from the cellar bellow, she recalled. Instead she tingled “with anticipation”.

The candles would be lit and kiddush made. She found “peace and warmth… it ignited my heart”. But when the house was sold two years after, the weekly Shabbat experience stopped.

Her grandfather was among those immigrants who had wanted to leave their ancestral religion behind in Europe and instead sought salvation in socialism; and thus she was raised without a religious upbringing.

But many years later, in her 70s, Pashman embarked on an experiment: she committed herself to exploring the meaning of Shabbat over the course of a year. Her reflections on her spiritual adventure resulted in her book, Journey to a Temple in Time, which was first published two years ago and is now available in paperback.

Shabbat is unique in being the only ritual that is included in the Ten Commandments. But for all its cardinal importance, many Progressive Jews have abandoned serious observance, she notes; it “shrank at best to a Friday night social”.

Could, she wondered, find an intellectually satisfying way to keep Shabbat for someone like herself who couldn’t “lay claim to an unquestioned belief in God”?

An academic philosopher who taught at Harvard, among other institutions, she has also written novels and short stories and the descriptive power with she recollects episodes from her own Jewish life give the book an emotional immediacy.

In her Long Island village of Sag Harbor, the local Jews gathered in a little community shul for Friday night but there were too few for a Saturday morning minyan so her first step was to start attending services at a Reform synagogue further away which included a post-kiddush class given by the rabbi.

Many of the regulars were happy to “warm themselves in the glow of a community”. But she was looking for a deeper rationale to maintain her day of rest.

The title of her book is taken from a phrase from Abraham Joshua Heschel, author of one of the most acclaimed modern studies of Shabbat, The Sabbath, who saw it as a “taste of eternity”. Along the way she cites ideas from a large cast of thinkers, Jewish and non-Jewish — Buber, Maimonides, Philo, Kant, Sartre, Spinoza and even Nietzsche. But while she can muster a formidable array of philosophical sources, the book always remains a personal annal rather than an academic treatise.

We meet living voices such as her friend and former student Lillian, who thinks that keeping a religious ritual without belief is “a waste of time”: and another student, Mike, a non-Jewish Italian, who took up Shabbat observance after a doctor told him he needed to lower his blood pressure — and who introduced her to the melachot, the 39 categories of forbidden work on Shabbat which the rabbis derived from the Torah.

As well as going to shul, Pashman initially decided to devote herself to “restful pursuits” such as reading, listening to music and walking. Gradually, she becomes stricter and while she does not fully adopt all the traditional prohibitions, she gives up use of a mobile phone and laptop and walks rather than drives to synagogue.

“You may pause on the Sabbath in order to improve your health or restore your mental balance or maintain family bonds, but in each case, we’re dealing with prudence, not morality,” she reflects.

She delves into concepts of God and of holiness and ancient practices. The Babylonians refrained from certain activities every seventh days, she learns, and each month held a festival for the full moon, Shabbatu.

Over the year more spiritual insights began to take root. Just as God rested from the act of Creation on the seventh day in the Bible, so Shabbat is a day set aside for contemplation when “the created world should be viewed as a work of art”.

But there is also an ethical dimension, which follows from the other reason given in the Torah for observing the Sabbath, the liberation from slavery. “I must reach beyond my own narrow perspective to see the world as an Infinite Being would, to view the concerns of others as equal to my own,” she concludes.

For all the arguments she rehearses, ultimately keeping Shabbat entails an emotional choice, a conscious act of freedom— “a decision to put spiritual concerns aheads of material ones during some part of each week”.

While we may tend to think of Shabbat in terms of a series of do’s and dont’s, Pashman reminds us that what is important is to be able to link our practice to a wider awareness; to have a philosophy of Shabbat, if you like. But our spiritual practice still needs to be grounded in concrete acts. As she counsels her grandson Jakey at the end of the book, “Light the candles, bless the bread and wine, and sing the songs.”

Journey to a Temple in Time - A Philosopher’s Quest for the Sabbath, Susan Pashman, Vallentine Mitchell, £19.95