Translate the following English sentence to French:
"The philosopher and theologian, Niebuhr, once said that a person' s sense of what is right makes democracy possible, but his inclinations in the opposite direction make democracy absolutely necessary."
Le philosophe et théologien Niebuhr a dit un jour que "le sens de justice de l'être humain rend la démocratie possible mais son inclination vers le sens inverse rend la démocratie nécessaire".