Occasionally, intellectual and cultural history is witness to what seems an astonishing coincidence of creative thinkers - the Lunar Society that formed in and around Birmingham in the late 18th century (Erasmus Darwin, Josiah Wedgwood, James Watt, Matthew Boulton, James Priestley), for example, or the Bloomsbury group in the early 20th (Virginia Woolf, Clive Bell, Roger Fry, John Maynard Keynes, E. M. Forster, Lytton Strachey).

Without reflecting on the conditions that might conduce to the congregation of genius or making the claim of priority explicit, Andrea Wulf has written a compelling collective biography of what may well have been the greatest of all such groups ever to have formed - which is to say, at once the most numerous and most influential: the set of philosophers and poets that flourished in the small university town of Jena in the Duchy of Saxe-Weimar for a brief period in the late 18^th and early 19^th century. In the 10 years between 1794 and 1804, Jena was home to a gathering of brilliant literary and scientific minds, all of whom would leave their mark, most of them for work they produced during this comparatively brief period.

The Jena Set can be dated roughly from Johann Gottlieb Fichte's sensationally popular inaugural lectures at the town's small but well-respected university in the summer of 1794, when a large proportion of the 800-strong student body clambered onto the benches and tables of the university's main auditorium to catch a glimpse of the famous post-Kantian philosopher and author of the characteristically ambitious Wissenschaftslehre or Theory/Science of Knowledge. Fichte could not be said to have inaugurated the Jena Set itself, however; he was personally far too arrogant and prickly to have initiated and sustained a group of friends.

That honour must surely go to the elder statesman and greatest genius of all the group: Johann Wolfgang von Goethe. Though, as privy councillor in the Duchy of Saxe-Weimar and its ruler Carl August's confidant, Goethe's primary residence was 15 miles away in Weimar itself, he kept rooms in the Old Castle in Jena where he would work for weeks on end and had already brought to Jena the playwright and essayist with whose name his own would remain eternally associated, Friedrich (later 'von') Schiller. In the summer of 1794, Goethe secured Fichte and Schiller began his Horen, a journal named after the Greek goddesses of the seasons, beauty, order, and justness which focused on art, culture, philosophy, and poetry. "And it was here, in the pages of Horen", writes Andrea Wulf, "that the Jena Set became a group for the first time".

Schiller's own Letters on the Aesthetic Education of Man (originally published in Horen) became the group's manifesto and, before long, Jena became the destination of choice for most of its brilliant contributors: critics and translators August Wilhelm and Caroline Schlegel; his brother, the novelist and essayist, Friedrich Schlegel, and the woman who would become his wife, Dorothea Veit; the philologist, diplomat, and educational reformer, Wilhelm von Humboldt, and his wife, Caroline, and (briefly) Wilhelm's more famous brother, the explorer and naturalist, Alexander von Humboldt. And with these came various friends and colleagues from their respective pasts, all with a distinguished cultural legacy to leave: the poets Friedrich Holderlin, Novalis (aka Baron von Hardenberg), and Ludwig Tiek, and philosophers Friedrich Schelling and Georg Wilhelm Friedrich Hegel.

If Goethe in part selected and sometimes managed the group of friends, however, by virtue of his status and wealth he remained somewhat aloof and his contribution occasional (though a perennial source of advice and mediation). The Jena Set itself, as it convened daily for creative conversation and argumentation in the rooms of the Schlegel house on the Leutragasse, was orchestrated by Caroline Michaelis-Bhmer-Schlegel-Schelling.

The concatenation of surnames tells the story of a succession of affairs and marriages and testifies to an emotionally and politically fraught life (as a young woman she had been imprisoned in Knigstein for her support of the French Revolution), but as the wife (though not lover) of August Wilhelm Schlegel, throughout most of the group's productive decade Caroline issued the invitations, oversaw the activities, and inspired the creativity of the group as a whole.

The Schlegels' companionate, open marriage worked well for both of them until it didn't. It enabled them to collaborate on the brilliant Shakespeare translations that were central to the German colonisation of the English playwright and are still in print to this day, as well as on the composition of hundreds of literary critical essays. But the marriage itself could not survive.

After a longstanding ménage à trois with Friedrich Schelling, the couple divorced, with Caroline eventually settling down with Schelling. August Wilhelm fled first to Berlin and his own ménage à trois with Sophie Bernhardi, then into the force field of the redoubtable Madame de Staël, becoming her companion and research assistant on the cultural history D'Allemagne [On Germany] that would publicise and promote to the world at large German culture and the German Romanticism that had been conceived and practised by the Jena Set.

Not surprisingly, in other words, the group was not without its tensions and (ultimately) betrayals. Schiller, early alienated from Fichte, would soon withdraw physically and emotionally from all of the Jena Set except Goethe. Again, it is hard to like the critically insensitive Friedrich Schlegel, who at one time or another found a bad word to say about everybody, in print and in private.

Indeed, sadly, at one time or another, every one of them can be found expressing her or his contempt for the intellectual or ethical shortcomings of another. Though Goethe's support and genuine friendship, it should be said, managed to survive all their misgivings and misprisions.

Like Madame de Stael's D'Allemagne, Andrea Wulf's Magnificent Rebels celebrates a high point in German intellectual and literary history, "a new confederation of minds" that found strength and glory in a newly liberated self. It is (as she says) a "magnificent" story and should, for that reason, end on a note of triumph.

The note we are left with, however, thanks to the thoroughness and honesty of Wulf's biographical account, is one of human fickleness and vanity.