The document outlines the evolution of vocal forms from the Middle Ages through the 20th century. It notes that in the Middle Ages, vocal forms were primarily monophonic religious works like Gregorian chant or polyphonic religious works like organum and conductus. Secular forms included the rondeau, ballada and virelai. In the Renaissance, religious forms included the mass, chorale and anthem while secular forms included the madrigal and villancico. The Baroque period saw the development of opera and oratorio while Classicism featured works like the symphony, sonata and lied. Romanticism focused on art songs and nationalist styles. The 20th century saw the rise of musical theater,