The Great Transformation: The world in the time of Buddha, Socrates, Confucius and Jeremiah, Karen Armstrong

In the wake of Antony Beevor's award-winning and bestselling accounts of the Second World War battles for Stalingrad and Berlin, the fashion in writing about the past for a general audience has switched in recent years to what publishers call microhistory - concentrating on a single event, confrontation or year in the life of a monarch. By such standards Karen Armstrong's The Great Transformation is flamboyantly bucking the trend for it covers a period of roughly 1,400 years in its 380 or so pages. Worse, they are 1,400 years from a long, long time ago and in countries and cultures far away from our own. And to cap it all Armstrong's chosen specialist subject is religion - something the well-bred Brit is taught to avoid raising at dinner tables and, by association, buying books about.

Armstrong, though, has a distinguished track record of going against conventional wisdom. Her History of God, the story of the 4,000-year quest for the divine, was rejected by many publishers as too obscure but went on in 1993 to become a bestseller on both sides of the Atlantic. Her subsequent writings on fundamentalism, Buddha, Islam and Jerusalem have made this one-time Catholic nun sought after and admired, especially in the United States where she gives summer schools for senators and congressmen keen to understand the religious forces that shape today's world.

The Great Transformation in many ways takes a giant step back in time from her previous work. It looks at a period between 800BC and 200BC, known to historians as the Axial Age, where key religious thinkers spread all across the globe fashioned religious belief in such a way that their reputations remain to this day - the Buddha, Confucius, Laozi, the mystics of the Upanishads, Plato, Socrates, Jeremiah, Ezekiel. Yet even if we are still familiar with their names and their works, Armstrong argues cogently, we are in danger of losing touch with what they actually said.

For what was remarkable about the Axial Age was that in different, totally disconnected places at the same time, there emerged a similar spiritual quest which was all about the struggle to live an ethical life. Practical rather than dogmatic, fluid rather than set in stone, the philosophy that emerged had as its distinguishing characteristics a search for enlightenment, a realisation that suffering was inevitable, a tendency to non-violence and a lack of interest in the sort of rules and proscriptions that today dominate theology. Indeed most Axial Age thinkers would not even have recognised what now passes for theology. What particularly linked them, Armstrong suggests, was their attachment to a single, all-embracing and positive golden rule - never do unto others what you wouldn't want done unto you.

Her narrative owes something to the Beevor school of microhistory in its attachment to detail. Her years-to-page ratio may be about 3-1 rather than 1-300, but she packs in the most extraordinary amount of information on the social, political, economic and spiritual details of the centuries she covers. Like a good thriller writer, she keeps four different stories up and running in parallel - one each in Israel, India, China and Greece. Out of particular and very different circumstances in each location, there emerges a remarkably similar denouement - Axial Age spirituality. So while the Jews were being banished to exile in Babylon, the Chinese were coping with the decline of the Zhou dynasty and the Greeks were enjoying the heyday of their city states. But in the end they arrived at roughly the same philosophical place.

There were wider common threads, including, at the dawn of the Axial Age, a new interest in writing down and codifying ancient stories and myths that gave rise to deeper reflection. And though Armstrong makes a convincing case for shaping her four civilisations into one in spiritual terms, she is candid in acknowledging that each embraced the various aspects of the Axial Age with varying degrees of enthusiasm. The Greeks, for example, had such a strong attachment to the heroic ideal that notions of non-violence were not as powerful as, for instance, in Israel which was forever torn and smashed by bigger, aggressive neighbours. Moreover, in explaining the ideals preached, Armstrong is not so naïve as to imagine that these were immediately translated into the realities of daily life.

The weight of detail, the complexity of the ideas and the vast span of history and geography in this book demand an unusual degree of commitment from readers. Armstrong has an easy prose style - pleasingly unacademic in tone - but nevertheless you have to concentrate hard because plot turns and twists come thick and fast.

In order to fortify her readers for the task ahead, and to reward them at the end, Armstrong uses her introduction and conclusion to transform the Axial Age from history into current affairs. Religion is widely credited in our world with causing conflict and suffering, not reducing it. We have grown terrifyingly accustomed to militant piety. Yet here she presents the roots of today's religions as something that is all about compassion, that is about commitment to an ethical lifestyle, that is about an openness to change and others' points of view. "We need to rediscover," Armstrong urges, "this Axial ethos. In our global village, we can no longer afford a parochial or exclusive vision. We must learn to live and behave as though people in countries remote from our own are as important as ourselves".

Key to that, she advises, are self-criticism of our own religious attachments and prejudices and plain old hard work and hard thinking to move beyond the artificial boundaries of dogma and denomination. If we need an example of just how rewarding and enlightening such a search could be, we need look no further than the remarkable and persuasive Karen Armstrong herself.