A ballet's choreography (arrangement of dance movements) may be based on such sources as a story, a musical composition, or a painting. If a choreographer's idea comes from a story, the dancers take the roles of the story's characters. If a choreographer's idea comes from music or a painting, the dancers create a mood or image like that of the original work. Few choreographers know what they are going to do when they start to rehearse a new ballet. Choreographers usually have only basic plans about what they want to create and the style of movement they want to use. They develop these plans with dancers at a rehearsal. It is almost impossible for choreographers to picture what the ballet will look like. Unlike most other artists, they cannot create alone. Choreographers seldom use words to develop and teach a new ballet. Most of them can dance, and they show the dancers the movements they want. The dancers imitate the movements until they learn their roles. Some choreographers demonstrate steps exactly. Others give a general demonstration, watch the dancers try it, and then get more ideas from them. Sometimes the choreographer may simply say something like "Please waltz around a bit," and then adapt something a dancer happens to do. Although all choreographers have their own methods, most of these specialists are influenced by the dancers with whom they work.