Accountant on a Ship

 An accountant, a passenger on luxury ship saw a passenger fall overboard. Panicking, she screams: "Help! someone's fallen over! Someone's fallen over!" The ship's second mate hears her and shouts: "Which side did they fall? Port? Starboard?" Accountant: Port...star...what?!?? (Then frantically points to the left) Debit side! Debit side! 

User Stories are not requirements

Treating user stories as requirements may not be too different from asking users to estimate how long it takes to do their tasks and using those estimates as your project estimates.

Santayana

Those who do not remember the past are condemned to repeat it.

Those who are not aware of the past are condemned to repeat it.

History repeats itself because the past is not the dead past but a mirror (albeit incomplete) of the very much alive present and future.