When Marcel Duchamp shipped Constantin Brancusi's sculpture Bird in Space to Edward Steichen in 1926, New York customs officials refused to accept that it was a work of art, instead levying the standard import tariff for a manufactured object. A legal battle ensued, with the courts eventually declaring Bird in Space an artwork and therefore exempt from the tariff. Seventy-eight years later, visitors to Simon Starling's exhibition at New York's Casey Kaplan Gallery were confronted with Staling's own Bird in Space (2004): a two-ton slab of steel from Romania (Brancusi's country of origin) leaning against the gallery wall and propped up on three inflatable cushions. The United States had recently introduced a new import tax of twenty per cent on foreign metals, which Starling circumvented by labelling this unaltered chunk of European steel a work of art. Its plinth of cushioned air not only introduced a second, more representational valance to the work but also brought to bear the traditional sculptural parameters of weight, gravity and balance. Starling's art frequently traffics in deception. It also traffics in traffic, meaning the circulation of goods, knowledge and people (usually the artist himself). Many of his works circle back on themselves, taking an idea on a journey that ends at its point of origin. Wilhelm Noack oHG (2006), for example, is an elaborate helical steel structure designed to loop a thirty-five-millimetre film of the workshop in which it was fabricated. The circuitous path that the film takes through the towering metal structure is the perfect visual metaphor for the work's own circular logic, a self-regulating system that adds up to much more than the sum of its parts. Starling is a key figure in one of contemporary art's most significant recent developments: the linking of artistic practice and knowledge production. Although this tendency flourished with Conceptual art in the 1960s and 1970s, in recent years it has taken on a new intensity. Unlike the Conceptual artists, however, many of whom strove for a language-based dematerialized art, for Starling the object is always at the work's heart. Economies, ecologies, coincidences and convergences are all simply means to an end -- although 'simply' may be the wrong word to describe the transformation of thousands of miles of travel and hundreds of years of history into a single sculpture, film or photograph. Starling's other predecessors are the Land artists, such as Robert Smithson, with whom he shares a fascination with entropy and other natural forces. But he is truly an artist of the current age, setting out to understand and illustrate the complex processes through which the natural and human-made realms interact. The five platinum/palladium prints that constitute One Ton (2005) show a single view of a South African platinum mine. Together the five prints contain the precise amount of platinum salts that can be derived from one ton of ore, succinctly illustrating the enor