Consensual contracts are such as are founded upon and completed by the mere agreement of the contracting parties, without any external formality or symbolic act to fix the obligation. Real contracts are those in which it is necessary that there should be something more than mere consent, such as a loan of money, deposit or pledge, which, from their nature, require a delivery of the thing, (res.) Inst. 3, 14, 2; Id. 3. 15′; Halifax, Civil Law, b. 2, c. 15, No. 1. In the common law a contract respecting real property (such as a lease of land for years) is called a “real” contract. 3 Coke, 22a