<p>Love letters are potent. They breathe. They speak. They can arouse, comfort, captivate. They can also cut deep. <br><br>The powerful, deeply personal letters collected here reveal the painful underside of love. Witness Winston Churchill 'growl with anger to be treated with benevolent indifference' and Edith Piaf reel in the throes of a 'terrible' passion. <br><br>Through the letters of literary icons Charlotte Brontë, Oscar...