by Jonathan Jones The dazzling, haunting ‘combines’ at the heart of Tate Modern’s forthcoming retrospective were part of a private game between Rauschenberg and his peers and sometime lovers, Cy Twombly and Jasper Johns Generous, big-hearted and political … Rauschenberg in front of his picture of President Kennedy. Photograph: Burton Berinsky/Time & Life Pictures/Getty Image   Robert Rauschenberg’s 1954 work Untitled is an upright wooden box supported by a white, colonial-era table leg over an open stage-like enclosure in which a stuffed Dominique hen struts next to a nostalgic photograph of a tall man in a white suit. Walk around this oddly compelling array – every surface of which is covered in old pictures, newsprint and smeared paint – and you find a pair of shoes, painted white. Do they belong to the man in the portrait? Who was he? Why does this constellation of stuff trigger such an undeniable, unforgettable sense of mystery?