Alexander Turney Stewart — Irish Businessman born on October 12, 1803, died on April 10, 1876

Alexander Turney Stewart was a successful Irish entrepreneur who made his multimillion-dollar fortune in what was at the time the most extensive and lucrative dry goods business in the world... (wikipedia)

You must never actually cheat the customer, even if you can. You must make her happy and satisfied, so she will come back.
You must be wise, but not too wise.