If, of all words of tongue and pen, The saddest are,'It might have been,' More sad are these we daily see: 'It is, but hadn't ought to be.'

-Harte, (Francis) Bret
  'Mrs.  Judge  Jenkins'.

   The rule of distributive justice is a statement of what ought to be, and what people say ought to be is determined in the long run and with some lag by what they find in fact to be the case.

-Homans, George C
  Social Behavior: Its Elementary Forms (rev edn).

Moulmein is situated up the mouth of a river which ought to flow through South America.

-Kipling, (Joseph) Rudyard
  From Sea to Sea.

Vous e"  tes libre, choisissez, c'est-a'  -dire, inventez. Aucune morale ge¤  ne¤  rale ne peut vous indiquer ce qu'il y a a' faire. You are free, therefore chooseöthat is to say, invent. No rule of general moralitycan show you what you ought to do.

-Sartre,Jean-Paul
  L'Existentialisme est un humanisme (Existentialism and Humanism,1948) (translated by Philip Mairet).