All mankind... being all equal and independent, no one ought to harm another in his life, health, liberty or possessions. John Locke
One ought to go too far, in order to know how far one can go. Heinrich Böll
What one has, one ought to use: and whatever he does he should do with all his might. Cicero
We would have to make clear to our German ally our disagreement on three points: treatment of the occupied countries, excesses towards the Jews, and relations with the Papacy. One ought to try to create a true European federation respectful of each nationality. Ugo Cavallero
One ought to hold on to one's heart; for if one lets it go, one soon loses control of the head too. Friedrich Nietzsche
No one ought to be judge in his own cause. English Proverb