Because a genuine enduring happiness is not possible, it cannot be the subject of art.
 Arthur Schopenhauer, The World as Will and Representation (1819). copy citation

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Author Arthur Schopenhauer
Source The World as Will and Representation
Topic happiness art
Date 1819
Language English
Reference
Note Translated by R. B. Haldane and J. Kemp
Weblink http://www.gutenberg.org/files/38427/38427-h/38427-h.html

Context

“for now there would remain nothing for it to do but to show that the glittering goal in which the hero expected to find happiness had only disappointed him, and that after its attainment he was no better off than before. Because a genuine enduring happiness is not possible, it cannot be the subject of art. Certainly the aim of the idyll is the description of such a happiness, but one also sees that the idyll as such cannot continue. The poet always finds that it either becomes epical in his hands, and in this case it is a very insignificant epic, made up of trifling sorrows, trifling delights, and trifling efforts—this is the commonest case—or else it becomes a merely descriptive poem, describing the beauty of nature, i.e., pure knowing free from will, which certainly, as a matter of fact, is the only pure happiness, which is neither preceded by suffering or want, nor necessarily followed by repentance, sorrow, emptiness, or satiety;” source