"Since ancient times, trees and vines have been trained for useful purposes, raising crops off the ground, increasing the yield of fruit and furnishing precious shade. The Romans were the first to develop these skills into topiary, the art of shaping plants to create living sculpture. In succeeding years, generation after generation of gardeners have favored topiary as a means of aesthetic expression, using it as a softer alternative to marble statuary and architecture, or as a pleasing counterpoint to the wilderness of unrestrained nature."
from Gallup, B. & Reich, D. (1987). The complete book of topiary. New York: Workman Publishing.