Social changes started in the late Middle Ages: painters, sculptors and architects began to be classed as artists. In the early days of the Renaissance, the arts started to compete with each other. Until then the fine arts had been subordinate to the artes liberales like music, but this was questioned by universally talented artists like Leon Battista Alberti (1404-1472) and Leonardo da Vinci (1452-1519). One key reason was the discovery of central perspective.