Pessimism, The Key To Happiness?

Roger Scruton defends negative thinking:

In order to see human beings as they are, therefore, and to schooloneself in the art of loving them, it is necessary to apply a dose ofpessimism to all one's plans and aspirations. I don't go along withSchopenhauer's comprehensive gloom, or with the philosophy ofrenunciation that he derived from it. I have no doubt that St Paul wasright to recommend faith, hope and love (agape) as the virtues whichorder life to the greater good. But I have no doubt too...