Wassily Kandinsky in his book “Point and Line to Plane” (Dover Publications 1925/1979) explains that “Every phenomenon can be experienced in two ways. These two ways are not arbitrary, but are bound up with the phenomenon--developing out of its nature and characteristics: Externally--or--inwardly. The street can be observed through the windowpane, which diminishes its sounds so that its movements become phantom-like. The street itself, as seen through the transparent (yet hard and firm) pane seems set apart, existing and pulsating as if “beyond.”
As soon as we open the door, step out of seclusion and plunge into the outside of reality, we become an active part of this reality and experience its pulsation with all our senses. The constantly changing grades of tonality and tempo of the sounds wind themselves about us, rise spirally and, suddenly, collapses. Likewise, the movements envelop us by a play of horizontal and vertical lines bending in different directions, as colour patches pile up and dissolve into high or low tonalities.