Some exhibitions have no need of fanfares, bunting, flashing light displays and interactive gizmos - absolute simplicity is all that's needed. This exquisite offering from the Ashmolean brings together 120 of Raphael's drawings, and very little else. The effect is rather gorgeous, and utterly absorbing.

Adding to the Ashmolean's world-leading collection of Raphael sketches, the exhibition brings together sheets on loan from the Albertina in Vienna, the Uffizi in Florence, and from various international collections including the Queen's. The works are presented chronologically, spanning the artist's early years in Urbino, through the honing of his craft in Florence, to the height of his career in Rome. Each individual piece is captioned in terms of the artistic process, the techniques employed, materials used, composition and intended visual effect, and the sketches increase in complexity as we move through the artist's life. High above the central exhibits a few shafts of light falling against the wall suggest a roughly sketched figure - an angel perhaps. A modest case of drawing materials such as the artist might have used gives context, and a few sections of the display include a small reproduction of one of the large, well-known and colourful masterpieces for which the sketches were studies, but the decision not to make much of these, and to let the drawings speak for themselves, is a deliberate one. The pared-down chronological approach and devotion to the core of the subject reinforce the fact that Raphael died when he was just 37, and the notion that the extraordinary mastery of the later drawings might have become all the greater is quite an arresting one.

The Ashmolean's Director Dr Xa Sturgis describes the exhibition as a once-in-a-lifetime experience, mainly because the delicacy of the drawings means they are not often lent by one museum to another, and are unlikely to be gathered together again for a long time. It's exciting to wander through a display of such significance, but it's the immediacy of the experience that makes it so illuminating. The dim lighting, which can sometimes make an exhibition seem quiet and lifeless, works perfectly here among the fruits of such concentration and industry. Examining from centimetres away the textured paper and the curve of each individual chalk-stroke, it really does seem as if each one could have been scratched just moments earlier - as if the artist has just stepped out for a minute, and as if the exhibition's hush is just an stretched-out momentary pause in an environment of activity. Seeing the sketches in the flesh, as it were, makes a great difference. The museum's lavish exhibition catalogue contains some really beautiful reproductions of items in the collection, but without being able to see the grain of the paper and assess the size of the sheets, you don't get the same sense of context and something, somewhere, is lost.

Much is made of the thought processes behind Raphael's art. The drawings allow us an insight into the dynamism of the creative journey, the intricacies of composition, the revisions and re-workings of form and stance, and the artist emerges as a master not only of visual representation, but of human emotion thus suggested: of the translation of violence, of struggle, of childhood, of humour, of religious ecstasy - of the sublime. Traditional religious subjects and classical scenes are interpreted with dynamic figures and naturalistic poses, a daring manipulation of sacred context which is invigorating and compelling.

Like other artists of the High Renaissance, Raphael manipulated the boundaries of realism to enhance the beauty and pathos of his images, without quite slipping into the Mannerist approach later developed by his contemporaries. The exhibition's co-curator, Dr Catherine Whistler, happily introduced the - to my mind potentially revolutionary - concept of Renaissance yoga, the no doubt creatively beneficial practice of attempting to adopt those beautifully drawn poses which look tantalisingly natural but could never quite be achieved in real life.

I enjoyed this glimpse of the other side of the serious process of setting up such an important and deeply rewarding exhibition, so sensitively and intelligently put together - where the lightest of touches unveils extraordinary intricacy and depth. And I enjoy imagining a visitor to the exhibition engaging in a little Renaissance yoga here and there, stretching the body and the mind in unexpected ways, alongside another, nose to frame, lost in a tiny detail of drapery or a lock of hair.

Raphael: the Drawings is advertised as a "once in a lifetime" opportunity. Well, it's certainly that, with loans from a range of international sources joining the Ashmolean's not inconsiderable collection.

The drawings range from rough sketches to final drafts ready to be worked up as an etching or the detail in a painting. At times, you can almost hear the thoughts of the artist across the half millennium since he put pencil or chalk to paper. You can see him wondering whether that group could be organised slightly differently, whether that head should be at a different angle or just doodling a few ideas for hands in the margins.

One noticeable feature is is Raphael's use of naked bodies. With most of the male nudes the focus is on musculature and the way in which bodies can be positioned to create dynamic three dimensional figures. In other drawings, it's simply about getting the underlying shape right – the figure will emerge in the finished work fully clothed, but the drapery of a dress will work because of the artists' attention to the body beneath it.

The strength of this exhibition is the way in which it allows you to compare many similar images, whether through a favourite subject, such as the Madonna and Child, or the development of a single work.

My favourite, if you can use "favourite" in connection of images of genocide, is a series of drawings for The Massacre of the Innocents (c. 1510). This brings together many of Raphael's key themes. All the male figures are naked – for the soldiers this means muscular, twisting bodies emphasising not only their strength and physicality, but adding the possibility of rape to infanticide. The little boys are also naked, highlighting the vulnerability of infant bodies protected by nothing more than puppy fat. Meanwhile, the usually benign theme of the Madonna and Child assumes a dark significance as the desperate mothers become so many Marys – each one making one last desperate contorted attempt to comfort and protect her child.

Ashmolean exhibitions come in a spectrum of difficulties and intensities ranging from widespread popular appeal to the more serious and academic. 'Raphael: the Drawings' is an excellent, well-curated exhibition at the serious and academic end of the scale and is most likely to interest those with a serious interest in art or the broader Renaissance period.