Happiness in the highest good is not indeed really meant to be the motive for virtue
 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 virtue
Date 1819
Language English
Reference
Note Translated by R. B. Haldane and J. Kemp
Weblink http://www.gutenberg.org/files/40097/40097-h/40097-h.html

Context

“In his highest good, which he afterwards discussed, we find virtue united to happiness. The ought originally so unconditioned does yet afterwards postulate one condition, in order to escape from the inner contradiction with which it is affected and with which it cannot live. Happiness in the highest good is not indeed really meant to be the motive for virtue; yet there it is, like a secret article, the existence of which reduces all the rest to a mere sham contract. It is not really the reward of virtue, but yet it is a voluntary gift for which virtue, after work accomplished, stealthily opens the hand.” source