Abstrakte Malerei

WebMuseum: Towards Abstraction
In 1911, a new group of German artists began exhibiting their work to the public. Der Blaue Reiter was to become the high point of German Expressionism, but it also opened the way towards abstraction with its stand for free experimentation and originality. It is Wassily Kandinsky, the most influential member of the group, who is most often credited with the distinction of painting the first ``abstract'' picture, in 1910.
http://www.oir.ucf.edu/wm/paint/tl/20th/abstract.html

WebMuseum: Pure Abstraction
Shapes and colors have always had their own emotional force: the designs on ancient bowls, textiles, and furnishings are abstract, as are whole pages of medieval manuscripts. But never before in Western painting had this delight in shape as such, in color made independent of nature, been taken seriously as a fit subject for the painter. Abstraction became the perfect vehicle for artists to explore and unversalize ideas and sensations.
http://metalab.unc.edu/wm/paint/tl/20th/pure-abs.html