that the farmer will produce a specific quality and quantity of wheat six months from now, but it is locked at today’s market price of wheat. so both are locking each other to a contract which is for the future. this contract has a life of its own. however, say drought happens and then the wheat becomes very hard to find and price of wheat will go high. so the farmer (who sees the value for the contract since wheat is going to be scarce) comes to miller and says that i will buy this contract off of you for some money (say $5k) and then the piece of paper 