... the form as a unit, and to consider here only what may be called the quality of line. A line may be straight or broken, and if curved, curving continuously or brokenly, etc. That this quality of line is distinct from form may be shown by the simple experiment of turning a spiral—a logarithmic spiral, let us say—in different ways about its focus. The aesthetic effect of the figure is absolutely different in the different positions, and yet the feeling about the character of the line itself seems to remain the same. In what sense, and for what reasons, does this ... — The Psychology of Beauty • Ethel D. Puffer
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