At least in art and architecture, classical standards as defined by the Greeks/Romans held sway for centuries. Those standards were questioned and challenged in the late 19th century and the 20th century by artists like Picasso and architects like Le Corbusier who believed that the "modern era" needed new forms of expressionism. I would say that the rapid pace of industrial, economic, and scientific development that began in the 19th century had a major role to play in creating those new forms.