A metaphor carries an idea from one area of thought to another. In literature and the arts, in planning, architecture and design, metaphors have a supremely creative role. They provide a system of thought that can supplement or bypass logic. Creative fusion of two entities takes place in a metaphor, as in sexual reproduction, to produce new entities taking genetic characteristics from each parent. Winston Churchill relished large-scale metaphors, and used them to manipulate large-scale concepts. This metaphor framed the Cold War period, from 1946 to 1989, and may have inspired the Berlin Wall. Churchill, like most English authors, admired the master of metaphor, William Shakespeare. Geometrical metaphors have been important in city planning and regional development. Planners speak of grid cities, radial cities and organic cities, though it is only the street patterns that have these characteristics. Anthropomorphic metaphors can also be used to plan spatial relationships.