Pastels have been loved for their vibrant colors since the sixteenth century, when Leonardo da Vinci was a fan. They surged in popularity in the eighteenth and late nineteenth centuries and are still a hit today. Pastels look so bright and lively because they don't contain any yellowing resins and reflect light from the finely ground powder. They're opaque, so they don't need super bright paper underneath to shine. In the eighteenth century, artists preferred using blue or gray paper for their slightly rough texture.