John Gardner said this quote
“ True art is by nature moral. We recognize true art by its careful, thoroughly honest search for and analysis of values. It is not didactic because, instead of teaching by authority and force, it explores, open-mindedly, to learn what it should teach. It clarifies, like an experiment in a chemistry lab, and confirms. As a chemist's experiment tests the laws of nature and dramatically reveals the truth or falsity of scientific hypotheses, moral art tests valyes and rouses trustworthy feelings about the better and the worse in human action. ”