There must be some one quality without which a work of art cannot exist; possessing which, in the least degree, no work is altogether worthless.
What is this quality? What quality is shared by all objects that provoke our aesthetic emotions?
What quality is common to Sta. Sophia and the windows at Chartres, Mexican sculpture, a Persian bowl, Chinese carpets, Giotto's frescoes at Padua, and the masterpieces of Poussin, Piero della Francesca, and Cezanne?
Only one answer seems possible - significant form.
In each, lines and colors combined in a particular way, certain forms and relations of forms, stir our aesthetic emotions.