“In art amuse emotions is a duty, to succeed is a plesure.”

According to The Veterinarian (Monthly Journal of Veterinary Science) for 1851, edited by Mr. Percivall, this is Ben Jonson's "satirical definition of physic".
Misattributed

Source: City of Ashes

Source: Murder on the Orient Express (1934)

1951 - 1968, The Creative Act', 1957
Context: I want to clarify our understanding of the word 'art' – to be sure, without an attempt to a definition. What I have in mind is that art may be bad, good or indifferent, but, whatever adjective is used, we must call it art, and bad art is still art in the same way as a bad emotion is still an emotion.
Therefore, when I refer to 'art coefficient', it will be understood that I refer not only to great art, but I am trying to describe the subjective mechanism which produces art in a raw state – 'à l'état brute' – bad, good or indifferent.

"Would you like to see a little of it?" said the Mock Turtle. (3 April 2010)
Unfit for Mass Consumption (blog entries), 2010
Context: Could anything be more inimical to art than a fear of emotion, or a fear of "excessive" emotion, or a reluctance to express emotion around others? No, of course not. Art can even best the weights of utter fucking ignorance and totalitarian repression, but it cannot survive emotional constipation.
I want a T-shirt that says, "Art is Emo." We live in an age where people are more apt to believe a thing if they read it on a T-shirt.

On art versus life in “Berkeley world premiere for Naomi Iizuka play” https://www.sfgate.com/performance/article/Berkeley-world-premiere-for-Naomi-Iizuka-play-3271229.php in SF Gate (2010 Mar 4)

Source: The 48 Laws of Power

Session 136, Page 280
The Early Sessions: Sessions 1-42, 1997, The Early Sessions: Book 3

Source: Dangerous