In the year of its completion, Crumb accepted a post at the University of Colorado, Boulder (1959–64) where, although employed as a piano teacher, his first mature works were composed. These include Five Pieces for Piano (1962), Night Music I (1963), which began as an instrumental composition but “came into focus” when he decided to set two poems by Lorca, and Four Nocturnes (1964). In all of them, delicate timbral effects combine with Webernesque pointillism and a wide range of references to create the atmospheric chiaroscuro that became a trademark of his style.