' Life is in continual motion. We perceive life externally and internally. art expresses our perception of life, not only the external perception but above all the internal. The more this perception fixes itself on the external the more superficial art is, the more this perception directs itself to the internal, the deeper, more spiritual and more abstract art will be.
Because the subject of art is eternally changing life, its means of expression is necessarily constantly changing. This continual change is the movement or evolution of art. Art is continually in movement because life commands it to be so and whenever it happens to us, such as now, that we do not understand the art of this time, it is not because art stands still, but because we do not move together with art. We stood still and art went past us. '
THEO VAN DOESBURG