This article summarizes one of the most significant developments in Western music history: the rise of polyphonic texture in the composition of sacred music. ¬†The earliest forms of polyphony in Europe were called organum. ¬†Organum reached its height at the hands of the composers at the Cathedral of Notre Dame in Paris. Leoninus and his successor Perotinus perfected a style of florid or melismatic organum that must have been astonishing to the people of their day. You’ll often see the French version of those composers’ names: Leonin and Perotin.