"I will make hay knots for you forever, if you give me a field" the farmer said.
the castle owner said, "forever means forever, have the field"
the farmer made 100 hay knots and gave 1 to the castle owner.
at some point, the farmer found oil under the field and decided to put a refinery on the field.
"I want to stop making hay knots, now." he told the castle owner. "I'll give you 100 hay knots today."
"Forever is forever" the castle owner said. "I don't want 10000 hay knots today."
"Fine, i'll buy a hay knot from the neighbor every year and give it to you."
----many years passed----
the oil refinery said to the castle owner, "we are not in the business of hay knots anymore, what will you take in exchange for not producing hay knots"
"I'll take the field" the castle owner said.