"Family business" joke

Once there was a Accountant. The business had been in the family for generations and generations. Over time, with the countless clients that had gone in and out of the office, the marble step in front of the building had developed a big, deep dip in it from all the wear and tear.
His friends kept telling the accountant that he had better get it replaced, otherwise he'd be sued for everything he had if anyone ever slipped and fell.
Reluctantly, the accountant called a stonemason to get a quote for the repairs.
When the stonemason got there the accountant demanded a price for a new step.
'Hmmmm, big job that'. said the stonemason, 'But I suppose I could give you a new step for a ten thousand rupees.'
The accountant was stunned. 'Are you mad, man? I can't pay you that much!'
Thinking about it for a second he turned to the stonemason and asked: 'What would you charge me to dig up the step and turn it over so that the worn part is in the ground and I'd get a new step?
The stonemason hesitated and said, two thousand'.
'Do it!' demanded the accountant, 'and call me when you're done.'
The accountant went back inside to his books, but after only 15 minutes the stonemason rang the bell.
As the accountant opened the door he saw the stonemason standing in a hole with the step, laughing as he said. 'Your great-great-great granddaddy thought of that a hundred and fifty years ago!!'