Don't assume anything is certain until you have it in your hand (in the case of money for example) or see it for yourself.
This saying is the moral of one of Aesop's fables. A milkmaid is given a pail of milk by her employer. She knows the doctor will buy the milk for a shilling and spends the journey thinking about how she will buy eggs with the shilling, which will hatch into chicks, which she can then sell for a guinea, which she will then use to buy a hat. Then she spills the milk!
Note: My reference sources tell this story using shillings (5 English pennies in pre-decimalization currency - i.e. pre 1970s) and guineas (21 shillings). However, on the assumption that Aesop didn't use pounds, shillings and pence in Ancient Greece - please feel free to substitute the currency of your choice!
British Parliament asks Amazon to clarify why it pays $9 million in income tax on $23 billion of UK sales.(May 20 2013) Amazon will be called back to give further evidence to members of the British Parliament "to clarify how its activities in the U.K. justify its low corporate...