Around the time of Bach's death in the middle of the eighteenth century, new forms and standards began to arise which would flourish until the more emotional Romantic music took over in the beginning of the nineteenth century. Reflecting the philosophical ideas of rationalism, music during the Classical Period became an art directed solely by the composer, with strict rules of harmony and structure reflected in the orderly contrasts of the sonata and symphony. Wolfgang Amadeus Mozart and Franz Joseph Haydn were two of the major proponents of these styles, writing reams of scores filled with short, clear phrases that expertly built and resolved tension within larger scaled forms. The piano became a major force, as dynamic compositions expertly utilized its new sound. Furthering the work of Mozart and Haydn, Beethoven was to become a bridge into the Romantic era -- his work boasted unexpected keys and a freedom from traditional harmonic rules, paving the way for freer and more personal styles of composition.