An ancient form of printmaking, still universally popular today, lithography stems from a chemical process based on the immiscibility of water and oil. Derived from the Ancient Greek, lithos (stone) and graphein (to write), lithography rose to prominences in the 18th Century, following the development of etching and aquatint. Using a stone or a metal plate with a completely smooth surface, a design is drawn in wax or other oily substances as a medium to transfer the ink to the printed sheet. The image may be directly printed from this plate (resulting in a reverse image) or offset by being transferred through a flexible sheet prior to printing. The process is widely used by artists such as Robert Rauschenberg, Jasper Johns, Pablo Picasso and David Hockney.