Why does art acquire a political meaning in the first half of the 19th century?

The political sound of European art at the beginning of the 19th century was given by the Great French Revolution. These great ideas of the revolution: freedom and universal equality, outside the estates, then inspired many prominent writers, artists, composers. Many of them were themselves participants in revolutionary events.
Thus, the ideas of freedom and civil liberties inherent in creative people spread throughout Europe and inspired representatives of the creative profession, giving art shades of political overtones.