The Vertical
The uplift of the [simple vertical] is spiritual as well as mechanical. It may carry the thought to higher levels or may support therewith an opposed line. In either case its strength is majestic and in so far as this line dominates does the picture receive its quality.
The Horizontal
A group of pines or the columns of the Greek or Egyptian temple alike induce solemnity, quietude and dignity. The horizontal is a line less commanding than the vertical with its upright strength, the symbol of repose, serenity, and reserved motion.
The Diagonal
The [diagonal] being an unsupported line naturally suggests instability, change, motion, transit. Its purpose frequently is to connect the stabler forms of the composition or lead therefrom.
The [curvilinear line] is the basis of variety and graceful movement. As an adjunct, it assists the sequence of parts. In the latter capacity it is of great importance to the composer. It is of course the basis of the circle as well as the important notion of circular construction and observation.
Given the subject and means of expression the final labor is the restraint or enforcement of parts in the degree of their importance. This requires ingenuity and knowledge and frequently demands a reconstruction of the original scheme.
Principality and Sacrifice
The most absolute and the most important idea in the production of art is Principality, that one object or idea shall be supreme. Its correlative idea contains in it the hardships of composition, namely, Sacrifice. This forces a graded scale of importance or attraction throughout the entire work.