The concept of the sculpture symposium began in 1957 with the Austrian sculptor Karl Prantl and friends. The idea being that sculptors come together for a period of time to make sculpture, exchange ideas, and share stories, knowledge and techniques. They often come from various countries, so they may not share a language.
Quite likely, the sculptor will not have worked with the particular materials of a given symposium, a particular type of stone, for example. So a degree of spontaneity and improvisation is useful for the artist. Often, the time period for sculpting is intensified -- from one to four weeks is common, occasionally five to eight weeks. The finished work usually remains with the community or entity that sponsors the symposium; some symposia allow the artist to take the work back after a year on exhibit, if it has not been sold.