"Endeavour to be beautiful, and then do at every moment that with which your heart will inspire you;" that is morality in a nutshell.
Notes from Wikiquote
As translated in Irving Babbitt, Rousseau and Romanticism (Boston: Houghton Mifflin Company, 1919), Ch. IV, p. 133.
Variants
Be beautiful and then do at each moment whatever your heart may inspire you to do. This is the whole of morality.