Full Idea
The Greatest Happiness Principle is a mere form of empty words unless one person's happiness, supposed equal in degree, is counted for exactly as much as another's (Bentham's "everybody to count for one, nobody for more than one").
Gist of Idea
Utilitarianism only works if everybody has a totally equal right to happiness
Source
John Stuart Mill (Utilitarianism [1861], Ch.5)
Book Reference
Mill,John Stuart: 'Utilitarianism (including On Liberty etc)', ed/tr. Warnock,Mary [Fontana 1962], p.319