What are some famous motifs in music and how do they contribute to the overall composition?

Some famous motifs in music include the "Dies Irae" in Classical Music and the "four-note motif" in Beethoven's Fifth Symphony. Motifs are recurring musical ideas or patterns that help unify a composition and create a sense of cohesion. They can be used to develop themes, create tension, or provide a sense of familiarity for the listener. Overall, motifs contribute to the structure and emotional impact of a piece of music.