An opportunity to see the work of printmaker Albrecht Dürer, known as 'Leonardo of the North', is one not to be missed, writes Aidan Dunne.

It's about 20 years since the Chester Beatty Library's Albrecht Dürer prints were placed on comprehensive display (a selection was on view at the Glucksman Gallery in Cork last year). That is the nature of the Library's collections: only a fraction can be shown at any one time. On this occasion, the Library's own Dürers (more than 120 of them, with just some duplicates not on view) are augmented by three drawings on loan from Bremen and Berlin. Even without the addition of these three pieces, you would be crazy to miss a chance to see an exhibition of this quality - particularly given that it may be 20 years before the opportunity arises again.

Dürer is particularly relevant to the Chester Beatty because its holdings are chiefly in the area of books, manuscripts and prints, and Dürer (1471-1528) was the first major European artist who chose to work primarily in graphic media. Although he did paint, with great virtuosity, drawing, woodblock printing and engraving were his primary activities. So there is no hint, as can be the case, that a show of prints is in some way an artist's second best. Prints are exactly what Dürer was about.

Of the pieces on loan, the most fascinating from an Irish point of view is his ink and watercolour study, Irish Soldiers and Peasants, much reproduced and seen here in reality for the first time. Made during a visit to Antwerp in 1521, it depicts a group of three gallowglass, heavily armed and stylishly attired, accompanied by two helpers.

Dürer, known as "Leonardo of the North" was, as curator Charles Horton puts it, "half artist, half scientist" in that he was a meticulous observer of the world around him, from flora and fauna to, here, the details of clothing and even the footwear of the men.

Dürer is also quite specific in identifying them as Irish. His own caption reads, in translation: "Thus go the soldiers of Ireland, beyond England/Thus go the poor (peasants) of Ireland." Quite what they are doing in Antwerp at that point in time is, Horton says, something of a puzzle. The men have a certain swagger about them, they look comfortable and confident. Their job, though, was generally to serve as bodyguards to Irish chieftains.

While Irish soldiers did find service as mercenaries in the Low Countries in the 16th century, 1521 is relatively early to find them so doing. Dürer's image is packed with information, and the Chester Beatty hopes to hold a seminar specifically on this drawing before the end of the exhibition's run.

Nuremberg, Dürer's birthplace, was a centre of trade and communication. Most importantly, perhaps, it was open to the humanist ideas emanating from Italy, and a spirit of optimistic inquiry characterises much of Dürer's work as an artist. He was, though, poised between the medieval and the modern worlds, and a great deal of what he did is clearly infused with a medieval spirit.

His father was a goldsmith. Dürer himself was a precociously gifted draughtsman and, after his apprenticeship, travelled as a freelance illustrator before returning to Nuremberg to marry Agnes Frey and settle down.

Engravings and woodcuts, Horton explains, were his bread and butter. He supplied a market for mostly religious and allegorical scenes and themes. What sets his efforts apart from the workaday is not only his enhanced ability, but also his insatiable curiosity about every aspect of the world, a curiosity that led him to visit Italy. In fact he made two extended trips to Italy and both had an extraordinarily invigorating effect on his creativity.

He worked phenomenally hard and was ambitious in the scope of his projects. The exhibition features his Apocalypse, consisting of 16 woodcuts on an exceptionally large scale and of dazzling technical virtuosity and visual inventiveness. Dürer published the volume himself, with a canny sense of timing. It first appeared in 1498, two years before the Apocalypse was predicted, according to a popular prophecy. Luckily the world didn't end, the book made Dürer's reputation and he went on to issue another edition.

Where he used the substantial size of the Apocalypse woodcuts to great effect, his set of engravings for the Passion go the other way. His engravings are, in general, very finely worked. Yet there is never a superfluous gesture. Every line does a job, shaping, defining, providing texture and tone. In the Passion of 1508, the images are more or less the size of playing cards, yet each is sumptuously rich in drama and detail.

After Dürer's death, Horton notes, there was a fashion for colouring in editions of his engravings. One such version of the Passion is included in the exhibition, worked over by a known Nuremberg colourist, Hans Mack. Without question, such is the quality of Dürer's linear tonality that the coloured version is inferior and colour is, in fact, superfluous.

One wall in the show is given over to what are generally regarded as Dürer's three Master Works, a stunning trio of engravings that really do exemplify his complete mastery of the art: Knight, Death and the Devil, Melencolia I and Saint Jerome in his Study. The trio seem to be generally related, though not overtly so.

That is, despite a great deal of scholarly attention, they have not been linked into any coherent iconographic scheme. Most obscure is perhaps the remarkable Melencolia I, in which a dispirited angel (the model was Agnes) sits, head in hand, surrounded by various emblems of scientific investigation and practical labour, with an emphasis on geometry. But these constructive symbols are overseen by Saturn, ambiguously signifying both dejection and mathematical endeavour.

Without pretending to great art historical insight, Gunter Grass wrote a brilliant essay - in fact a lecture - on the engraving during the 1969 election campaign, in what was then West Germany. His piece forms the epilogue to his book From the Diary of a Snail. He sees Dürer as caught between the medieval and modern worlds. Dürer pictures, he says, "the state of reactive melencholy prevailing in the age of humanism . . . The Middle Ages are still present".

Against a background of great religious uncertainty, the reformation was pending. The humanist enterprise was barely under way. Progress is dogged by stasis. Dürer was acquainted with the Italian philosopher Marsiglio Ficino's book on "Saturnian Man". Ficino's plight echoed Dürer's: a scientific humanist "dismayed to find himself believing in the power of the planets, and looking upon melencholy as a Saturnian calamity".

But melencholy, he was persuaded, could be, as Aristotle argued, a fruitful thing, a brooding state from which great thoughts could emerge. Just so. Dürer's lively intelligence, his open curiosity and visual brilliance are evidence of that.

* Albrecht Dürer is at the Chester Beatty Library until Feb 7, 2006.