The Chester Beatty Library, in Dublin Castle, which is hosting next week's conference on understanding Islam  houses an outstanding Islamic collection.

In 1912 the New York-born entrepreneur Alfred Chester Beatty (1875-1968), already a wealthy and assiduous collector, and a widower, married for the second time. He and his bride, Edith Dunn, honeymooned in Egypt. They were so taken with the country that they subsequently bought a house in Cairo. It became their annual winter residence for about 25 years, proving an ideal base from which Beatty, who became a British subject in the 1930s, could deepen his interest in, and knowledge of, Islamic culture. It also allowed him to widen his circle of dealers and agents, his aides in procuring a wealth of Islamic books and manuscripts. Nor was he too egotistical to refrain from enlisting expert advice, helping to ensure that he bought only the best.

Having moved to Dublin in 1950, Beatty went on collecting well into the 1960s - though perhaps the high point for his acquisition of Islamic material was the 1930s. By the time of his death his collection, which he bequeathed to the State, included about 4,000 manuscripts, paintings, book bindings and other objects.

As well as outstanding illuminated copies of the Koran, the library holds superb Mogul, Turkish and Persian manuscripts. Copies of the Koran, though often brilliantly illuminated, are never illustrated. The decoration is rigorously abstract. Calligraphy has a special status in Islam. The Koran is believed to be literally the word of God, and the Prophet Muhammad is credited with a statement to the effect that fine calligraphers will have no difficulty in entering paradise.

There is, however, plenty of scope for illustration in other contexts. The library's collection of Indian miniatures from the days of the Mogul emperors, documented in two big, dense volumes by Linda York Leach, is stunning. There's more than enough to justify the catalogue's opening remark: "It would be difficult to discuss the history of Mughal miniature without reference to the Chester Beatty Library . . ." Equally dazzling are Persian and Ottoman miniatures and manuscripts.

Apart altogether from obvious aesthetic considerations, though, many of the Islamic manuscripts in the library are works of scholarship. As Elaine Wright, the curator of the Islamic collections, writes: "The majority of the Islamic manuscripts have no decoration whatsoever, neither illuminations nor illustrations." They are, essentially, like reference books and texts, many of them now unique, covering a huge range of subject matter, including "history, geography, medicine, astronomy and astrology, statecraft and the religious sciences". As such they are primary research documents.

• Understanding Islam, a three-day public conference on the culture and religion of Islam, is being presented by the Chester Beatty Library at Dublin Castle's conference centre from December 6th to 8th. Advance registration is recommended, as places are limited. Telephone Lisa Fitzsimons for information on 01-4070779 or see www.cbl.ie