A new approach to making carved sculpture introduced by Brancusi from about 1906. Before that carved sculpture had always been based on a carefully worked out preliminary model. Often it was then actually carved by craftsmen employed by the artist. The marble sculptures of Rodin were made in this way. In direct carving there is no model and the final form evolves through the process of carving. An important aspect of direct carving was the doctrine of truth to materials (see also Impasto). This meant that the artist consciously respected the nature of the material, working it to bring out its particular properties and beauty of colour and surface. Direct carvers used a wide variety of types of marble, stone and wood. They kept to simple forms which respected the original block or tree trunk. Surfaces were kept uncluttered by detail in order to expose the material itself, and were often carefully polished to enhance the colour and markings. The results were often highly abstract. In introducing direct carving Brancusi brought about a revolution in the tradition of carved sculpture. After Brancusi, notable direct carvers were Epstein, Gaudier-Brzeska, Hepworth and Moore.