In the broadest sense, the theory or practice of any of several groups of recent painters, or of these groups taken collectively, whose work and theories have in common a tendency to reaction against the scientific and naturalistic character of impressionism and neo-impressionism. In a strict sense the term post- impressionism is used to denote the effort at self-expression, rather than representation, shown in the work of Cézanne, Matisse, etc.; but it is more broadly used to include cubism, the theory or practice of a movement in both painting and sculpture which lays stress upon volume as the important attribute of objects and attempts its expression by the use of geometrical figures or solids only; and futurism, a theory or practice which attempts to place the observer within the picture and to represent simultaneously a number of consecutive movements and impressions. In practice these theories and methods of the post-impressionists change with great rapidity and shade into one another, so that a picture may be both cubist and futurist in character. They tend to, and sometimes reach, a condition in which both representation and traditional decoration are entirely abolished and a work of art becomes a purely subjective expression in an arbitrary and personal language.