Book - 9 and Puzzle - 6

Last time I had asked following puzzle

A man and his son met with a car accident. The father dies on the spot, but the boy is rushed to hospital. The surgeon on duty says, ‘I would not like to operate on this boy, he is my son.’ How can this be?
In response to it, I received more e-mails than I could handle. The answer that Surgeon was the mother of the boy, is not as easy as it appears.  Many have preconceived notions that surgeon has to be a male. There was one e-mail from US suggesting that the couple could be a gay couple, the surgeon could be male.  It gave new insight to me.  I could not have imagined this, as gay marriages are illegal in India but are legal in some states in US. Another email suggested that person who died in the car accident could be a priest as they are also called fathers and the surgeon could be the biological father.
This puzzle is an example of lateral thinking.  On many occasions, lateral thinking is an effective way of getting into right answer rather by solving it by logical or vertical thinking. If you are interested in reading some good books about lateral thinking then you will enjoy reading 'Lateral Thinking' and  'The Use of Lateral Thinking' both written by Edward de Bono, The other good books are 'Thinking About Thinking' by Antony Flew and 'Straight and Crooked Thinking' by Robert H. Thouless. Here is another puzzle, which can be satisfactorily solved only by use of lateral thinking.
'Many years ago when a person who owed money could be thrown into jail, a merchant in London had the misfortune to owe a huge sum to a money-lender. The moneylender, who was old and ugly, fancied the merchant's beautiful teenage daughter. He proposed a bargain.  He said he would cancel the merchant's debt if he could have the girl instead.
Both the merchant and his daughter were horrified at the proposal. So the cunning money-lender proposed that they let Providence decide the matter.  He told them that he would put a black pebble and a white pebble into an empty money-bag and then the girl would have to pick out one of the pebbles. If she chose the black pebble she would become his wife and her father's debt would be cancelled. If she chose the white pebble she would stay with her father and the debt would still be cancelled.  But if she refused to pick out a pebble her father would be thrown into jail and she would starve.
Reluctantly the merchant agreed.  They were standing on a pebble-strewn path in the merchant's garden as they talked and the money-lender stooped down to pick up the two pebbles. As he picked up the pebbles the girl, sharp-eyed with fright, noticed that he picked up two black pebbles and put them into the money-bag.  He then asked the girl to pick out the pebble that was to decide her fate and that of her father.
Imagine that you are standing on that path in the merchant's garden.  What would you have done if you had been the unfortunate girl? If you had had to advise her what would you have advised her to do?' 

It is often said that originality is borrowed. This puzzle is  starting paragraph of the book 'The Use of Lateral Thinking'