A Notebook at Random shows Penn to be the most successfully experimental photographer of the last 100 years. For example he juxtaposes an image of a deliberately distorted face on one page with one of his most striking, beautiful portraits on the next and, by doing so, makes us look at the human visage from a completely different perspective. Side by side the images enhance our wonder at the beauty and balance of our faces but also imply the their fragility. He does a similar thing with his images of the human body - an enormously tender photograph of 3 naked couples in various embraces that captures compassion, dependence and sensuality is placed next to a distorted image of the human body that looks like a photograph Francis Bacon (someone Penn had photographed in London) might have taken had he been using a camera not a paint brush.

Furthermore, the photographs are set against his drawings and paintings which implies how, no matter what the commission (fashion or otherwise), Penn always sought to create images that had artistic merit as well as commercial impact. I particularly like the surrealism of some of his still life studies - fish that look almost like phalluses lie next to skulls; vegetables are photographed to create the features of a face, as if Penn had looked at Archimboldo's paintings and stripped away all of the Italian painter's flourishes to leave only the eyes, nose and mouth represented.

Turn more pages and we are confronted by two disturbing photographs that make powerful statements about the female condition. A naked woman who is photographed from knee to just below her breasts and, therefore, whose face we cannot see, lies on a sheet wearing a cruel metal chastity belt. It is as if the belt has deprived her of her identity and thus taken away more than just her choice to have sex with whosoever she wishes. Another turn of the page brings us to a photograph entitled Football Face which shows a, presumably, naked female from the shoulders up, but whose face is completely covered by an American football, worn like a grotesque, smothering mask. The football is framed by her hair. and we see none of her features. The ball's laces face the viewer. In effect, she has been laced up, given no chance to express herself either verbally or visually. And the American football is, of course, one of the most iconic symbols of male power and identity in the USA, something carried aggressively, battered and kicked during this most violent of sports.

One moment we are in awe of his control of light and shape to create images of extraordinary beauty, the next we are deliberately unsettled by images that challenge our perceptions andvalues.