The visual arts in Russia are rooted in lubok but this begins to change in the reign of Peter the Great that is an "alternate" tradition of social and political caricature. Artists from western Europe contribute to this cultural shift by teaching at the Imperial Academy of Arts in Saint Petersburg. The Academy's charter is revised by Catherine the Great and again in 1840 by Nicholas I. Nicholas assumes power in 1825 establishing new censorship committees after the Decembrist revolt that same year. During this time it becomes prohibited for artists or writers to mention political officials by name or to represent political views in their work. Censorship continues to expand in the upcoming decades. In 1840 the royal family is given control of the Academy and in 1848 the Buturlin Committee is formed in response to the Revolutions of 1848. Private art schools continue to operate in this era but artist's are for practical purposes dependent on state and imperial support for a living. After 1851 the lubok folk art must be destroyed and new works to carry the censor's seal but unauthorized works were still made until the second half of the 19th century. These uncensored "lubki" depicted the religious, literary and other themes and motifs of folklore common for this art form.