THE original Fountains Abbey wasn't quite the glorious structure whose breathtaking ruins we see today. The first monks sheltered under rocks. Then they built a hut of wattle and turf beneath a spreading elm.

As late as the eighteenth century, a rotted stump known as the Fountains Elm was recorded 500 yards east of the abbey, on the north bank of the River Skell. For those who know their Fountains, this is immediately on the abbey side of Tent Hill, the mound that divides the former abbey precinct from the Studley Royal water gardens.

What a shame this historic birthplace isn't marked - ideally by an elm. An information panel or plaque might quote Glyn Coppack who, in an absorbing new history of the abbey, suggests: "It may have been the choice of the Fountains' monks to seek the hardest possible beginning for their house."

Within their hut, the monks mixed leaves from their elm with herbs and water to make a thin gruel. On this, they subsisted while they built a modest oratory, or prayer house.

Within a year or so, they shifted to the present site, where they erected timber buildings whose post holes have been found at the heart of today's abbey. But though the wooden monastery heralded what was to become one of the greatest monastic complexes in Europe, Coppack stresses that the monks were "indifferent to buildings".

Destined to join the Cistercian order, they shared the view of its leader, Bernard of Clairvaux, that while impressive buildings "attract the eye of the worshipper, they hinder his attention".

Cistercian rule completely banned towers. Yet at Fountains, the soaring "Abbot Huby" tower is a defining image of the abbey. And more than two centuries before it was built, the abbey's first historian, Hugh of Kirkstall, writing in 1206, referred to the abbey's "sumptuous buildings". How did this lavishness come about?

Essentially a story of wealth sapping early spirituality, the transformation of Fountains from the simple to the sophisticated, if also the sublime, forms the core of Coppack's admirable book. It is the outcome of a close association with the abbey by the author, a senior English Heritage inspector who has directed excavations at Fountains over a period of 25 years.

"It is rare that I visit and do not find something new," he remarks. And the many lovers of Fountains are sure to find something new in Coppack's lucid account of what he calls "the most informative of any Cistercian abbey in Europe".

As he explains, the Cistercians began as a breakaway sect dedicated to restoring the ideals of strictness and austerity set in the sixth century by St Benedict, the founder of monasticism. Settling on swampy land near Dijon in France in 1098, they took their name from the Latin word for marsh, cisterna. Quickly dubbed the "New Soldiers of Christ", they wore white to symbolise purity and distinguish themselves from the Benedictines, and they reduced ceremonies to increase the time spent in manual labour, reading and prayer - the three activities by which they aimed to serve God.

Preceded in Britain only by the abbeys of Waverley in Surrey, and Tintern, Rievaulx Abbey, founded directly from France in March 1132, was the first Cistercian house in the North. It almost certainly gave the cue to a dozen or so disenchanted monks at the Benedictine St Mary's Abbey, York, who at Christmas 1132 settled at Fountains on land provided by York's archbishop.

WHAT is surprising is how quickly the founding ideals were softened - or rejected. Perhaps finding the elm gruel intolerable, two monks returned to York almost immediately. In 1157 the "towers ban" was eased to a ban on towers with bells. So a new stone church built soon after at Fountains boasted a fine lantern tower.

Serving a smaller community than Rievaulx's, the church was much larger and, notes Coppack, "was meant from the first to demonstrate the wealth and importance of the abbey". He adds: "By 1180, after less than half a century, the buildings of Fountains Abbey had achieved a greater scale than any other house of the order in England."

But the peak hadn't been reached. Already diverted about 28 yards, the Skell was tunnelled to create a wide platform of land. On this arose a so-called "infirmary" - in reality a self-contained monastery for the old and infirm, with one of the largest aisled halls in medieval England.

And in the fifteenth century the lantern tower yielded to the even grander Huby tower. Complete with bells, it also displayed an elaborate inscription offering "honour and glory for ever to the Only God". Yet Abbot Huby's initials were all over the abbey.

By now its extensive estates stretched throughout Yorkshire and beyond. A carefully-organised series of granges included a northern chain that ran via Cowton, near Northallerton, and Busby, near Stokesley, to Eston and a Teesmouth fishery. Urban properties were owned in Scarborough, York, Yarm (then the port of the Tees), Ripon and other centres.

Officially forbidden to buy land, the monks nevertheless did so. Hamlets that obstructed expansion were removed. And with wool the foundation of the abbey's wealth, the monks indulged in stock-exchange-like speculation on prices, which ultimately plunged the abbey to near-bankruptcy with debts of £6,373.

"The founding community would have been appalled, not only by such dreadful mismanagement but also by the willingness of the monks to involve themselves with money," comments Coppack. "Gone was the simplicity of the life they had sought."

Yet the personal wealth of monks had been a crucial early lifeline. Two years after pitching up under that elm, the still-struggling community petitioned for closure. But on his return from France, with permission to abandon the fledgling monastery secured, the abbot found the abbey saved. By retiring to Fountains, three wealthy canons from York provided financial security, which soon led to the first endowments of land, rapidly followed by many more.

Another key figure was Sir Richard Gresham, who bought the abbey on its suppression in 1539. More interested in its home estates than its buildings, he did little more than render the buildings unfit for use, chiefly by removing the roof and lead, as demanded by Henry VIII.

"It is largely because he only carried out the work he was required to do that Fountains remains one of the most complete Cistercian monasteries of the medieval period," observes Coppack.

THOUGH not central to his theme, the later developments at Fountains, notably the abbey's integration into the great water gardens of John and William Aislabie, are broadly described by Coppack. But he emphasises that much remains to be learned about the abbey itself, where at least 21 buildings remain to be excavated.

Launched in 1966, a comprehensive programme of conservation, excavation and study still has 20 years to run.

"Quite simply," says Coppack, "Fountains will be the best known and understood medieval monastic site in the world."

Hopefully, he will be around to update his fascinating account of the story so far.

* Fountains Abbey: The Cistercians in Northern England by Glyn Coppack (Tempus, paperback, 100 illustrations, 25 in colour, £15.99)