“Modern Art: In strict historical terminology, modern art began in the middle of the 19th century with the realism of Gustave Courbet. At that time, art began to free itself from the strict requirements of subject matter and developed increasingly toward preoccupation with form. In general, it also repudiated many of the techniques of pleasing the viewer devised by past canonical artists.”
Excerpted from: Diamond, David G. The Bulfinch Pocket Dictionary of Art Terms. Boston: Little Brown, 1992.