Written over a period of 18 years, Rachmaninov's sets of Preludes are a mirror and a record of his compositional development. With so rich a variety of character, color, texture, and mood, no two preludes are fully alike, and differentiation of tempo and register ensures that each prelude's character is clearly defined. The first eleven pieces were conceived by Rachmaninov as a single cycle, and their full-hearted Romanticism contrasts with the significantly more angular, modernistic Op. 32. Whether evoking ballad or bell toll, the exotic or folk influences, the Preludes stand in the great tradition of works by Bach and Chopin written in all 24 major and minor keys.