Oh, when I was in love with you, Then I was clean and brave, And miles around the wonder grew How well I did behave.

-Housman, A(lfred) E(dward)
 A Shropshire Lad, no.18.

We are all the President's men, and we must behave accordingly.

-Kissinger, HenryAlfred
  On the US invasion of Cambodia, alluding to the nursery rhyme Humpty Dumpty ('All the king's men†'). The phrase was used in the title of the book by  Washington Post reporters Bob Woodward and Carl Bernstein on the Watergate scandal.

Il ne faut se permettre d'exce'  s qu'avec les gens qu'on veut quitter biento"  t. We should never permit ourselves to behave in excess except with those whom we will leave soon.

-Laclos, Pierre-Ambroise Choderlos de
  Les Liaisons dangereuses, letter10.

Do you think that the things people make fools of themselves about are any less real and true than the things they behave sensibly about? Theyare more true: theyare the only things that are true.

-Shaw, George Bernard
  Marchbanks to Morell. Candida, act1.