The Eighteenth Amendment was the result of decades of effort by the temperance movement in the United States and at the time was generally considered a progressive amendment.
In a sales contract, the parties are the seller(s) and buyer(s) of the real estate, who are often called the principals to distinguish them from real estate agents, who are effectively their intermediaries and representatives in negotiation of the price.
Definition. An agreement in which the seller conditions the sale of one product (the tying product) on the buyer's agreement to purchase a separate product (the tied product) from the seller.