On its technical side, Cubism is simply a systematic use of planes.
The power of lines is a manifestation of the new mode of representation.
It is not a semblance of things, but a world of objects that the picture forces us to take in with a glance. The objects may not get lost. The outline is the demarcation and designation of the objects. By its outer essence their inner nature is expressed. The nature of objects is not fixed by a correct drawing, but by a forceful and emotional, intensive and pervasive outline. Not in their restfulness and with their details do the objects serve the picture, but by their relations to each other, which relations combined lead up to the climax.
The long lines form the structure of the picture. They decide how the picture is to be constructed from its parts, and how the parts are to be interlocked in order to become a whole. The long lines define the measure and rhythm of the work. Lines are the vibrations of the soul; lines are reflections of the will, the rigidity of that which endures. Like currents of forces they flow against each other and unite into one. The smaller ones accompany them with playful gambols, like a multiple echo, the sounds of which melt away in the distance.
The picture is not a nicely divided plane. It is like a world arising from chaos. Its essence is the law of order working itself out. The picture is an agglomeration of agitated members, an agglomeration of planes pulsating with blood, enlivened by breath.
The planes may be stratified, parallel and similar to each other; they may rear and pile themselves against each other, or they may interlock like cogs. They may liquefy and melt away, or they may double up and form themselves into balls. They may, more quietly, rest within themselves, becoming effective through the contrast of their essence and yet maintaining themselves. Out of them originates the picture’s spaciousness, out of them the living force of the picture.
The dynamics of the planes is a manifestation of the new style.[36]
DUCHAMP