The place of balance theory in contracts

Barter contracts, such as sales, are a good place to look at the balance rule. The ancients easily understood that sale is based on three equations: a) Acquisition vs. Acquisition, b) The balance of Arash Awadin, c) Surrender vs. Surrender, so that the first and second equations are the prelude to the third equation. The above three equations in the contract of sale are an example of the general rule of equilibrium.In inferring from the above three equations, the defective option can be extracted and said: The sale is based on the rule of equality between the parties, so if after the contract it is found that the seller has a defect, the equality of the parties is disturbed and the customer is right. Is to demand from the seller what has died due to a defect according to the contract of sale, and since the seller of the defective property is unable to submit a description of health (because the seller was the same person), the solution is to give the right of choice to Customer.