WHAT IS A SONG CYCLE?
A song cycle is a group or cycle of two or more songs that share a common theme or central idea, designed to be performed in a sequence. Song cycles are derived from a poem, a story line, a central theme or topic such as love or nature.
Song cycles are usually for solo voice or a vocal ensemble. On rare occasion, a combination of solo songs may be mingled with choral pieces arranged as a song cycle.
Song cycles can be traced as early as the 13th century, but the term song cycle did not flourish until the 19th century. The greatest influence of the song cycle was the German lied, or poems set to classical music.
Look at an excerpt of Mondnacht from Lederkreis by Robert Schumann.