Part entered several periods of contemplative silence, during which he studied choral music from the 14th to the 16th centuries. He studied plainsong, Gregorian chant, and the emergence of polyphony in the European Renaissance. After this period, the music that started to emerge was radically different. Some of his most well-known pieces were written at this time including Fratres, Cantus In Memoriam of Benjamin Britten, and Tabula Rasa. The music from this period is described as tintinnabuli - like the ringing of bells. The music is characterised by simple harmonies, often single unadorned notes, or triads, with simple rhythms and non-changing tempos.