With the world being plunged into crisis after crisis, it is tempting to ask if we have the right leaders to see us through. Most world leaders today are intelligent, sombre, cautious and well-educated people. Just think of Germany's Angela Merkel and US President Barack Obama. One is a trained physicist and the other a constitutional law specialist. Though not quite a world leader, our very own Donald Tsang Yam-kuen is cast in this mould. And they are all showing signs of failing. That may be why a new book called A First-Rate Madness by American psychiatrist Nassir Ghaemi has caught the public attention and become a bestseller. He argues that normal leaders - people who are just like you and me except a little smarter and more knowledgable - may not be the most effective in times of crisis. Leaders who are a little unhinged, who suffer from manic depression, or bipolar disorder, may be just what the world needs in a time of crisis. Most of us would consider wild mood swings to be a drawback for a political leader, but Ghaemi says such people can be extraordinarily resilient, creative and determined. He seems to be describing the charismatic personalities the 19th-century writer Thomas Carlyle called the true engine of history. An obvious example was Winston Churchill, who suffered from bouts of deep depression and periods of heightened excitement. But one could just as easily cite Hitler or Mao Zedong . Betting on such personalities seems to be an all or nothing proposition. That's why cautious, sensible leaders muddling through may be preferable to those who promise us paradise but deliver hell.