Most of us resist any distortion of a recognizable image. Yet the artist must distort or modify form, not only in order to express his ideas, but to preserve the unity of the picture plane. All spaces must be designed so as to maintain an exchange of importance with one another. When the design is successful, nothing can be added, nothing taken away. All relationships must be established and united through this exchange of equality.
The privilege and necessity of design to distort for the sake of unity has always been an instinctive device in the arts of primitive cultures. ...
... Distortion for distortion’s sake would be just that. But distortion in order to let “no-thing,” the background, have reality, “thing-ness,” produces harmony and an exchange between the forms.
When we begin to work in art, we find that we do not mind distorting some kinds of things that can actually grow in deformed ways—trees, for instance. But what about a chair or a chimney? Man-made structures or functional objects are the most difficult for us to distort. Here our resistance is greatest, for objects designed for a utilitarian purpose must maintain their shapes and proportions in order to serve their functions.
Dorr Bothwell and Marlys Mayfield
“Notan: The Dark-Light Principle Of Design”