In 1959 Tucker turned to metal construction as an alternative to modelling and carving. Reacting against the narrative or symbolic content of much 1950s sculpture, Tucker insisted on abstractness. Central to the abstract sculptures he began to make is his idea of 'sculpture as thing in itself'. He meant that the work should have a definite character in itself, without representing some other thing. In pursuit of this aim his works emphasise some essential consituents of sculpture: notably materials (welded steel) and process (construction). '37' is an early work which introduces humour and ambiguity by treating numerals, which are recognisable, as though they were abstract shapes.