Full Idea
The acquisition of pleasure for oneself rarely, if ever, presents itself as a duty, while the attainment of moral goodness habitually presents itself as a duty; this surely points to an infinity superiority of virtue over pleasure.
Gist of Idea
Virtue is superior to pleasure, as pleasure is never a duty, but goodness is
Source
W. David Ross (The Right and the Good [1930], §VI)
Book Reference
Ross,W.David: 'The Right and the Good' [OUP 1930], p.151
A Reaction
You have to be a fully paid-up intuitionist (like Ross) before you can assert such gloriously confident judgements about duty. Personal pleasure could become a duty if you had mistakenly denied it to yourself for a long time.