In the Anglo-American common law, formation of a contract generally requires an offer, acceptance, consideration, and a mutual intent to be bound. Each party must have capacity to enter the contract. If you run a business, and have an existing employment agreement with an employee, and need to alter it, you can use an Employee Agreement Amendment. Sometimes changes are necessary if the work responsibilities have shifted, or if you'd like to reward an employee with more vacation days. An Employment Agreement Amendment is useful when you want to change only one or two terms in an existing contract. Here is an appropriate provision that was taken from the sample NDA in the previous section. Even if they are good in one jurisdiction, they may not work in another. And the facts of your situation may make these forms inappropriate for you. Selfridge Lord Dunedin adopted Pollack's metaphor of purchase and sale to explain consideration. He called consideration 'the price for which the promise of the other is bought'.