Contracts which derive their efficacy from the substance of the transaction rather than its form are called simple contracts. The essential requisites for simple contracts are the mutual assent of the parties and consideration. Such contracts may be either oral or in writing. Except so far as Statutes of Frauds 37 or other enactments 38 have changed tie common law there is no difference except in matters of procedure and proof between oral and written contracts. Both are classed as parol contracts.39 Assumpsit was the appropriate remedy for tury-Ames, 2 Harv. L. Rev. 56, and the common remedy until the eighteenth century when the action of covenant became more common. 3 BI. Comm. 154.

36 See 8 Harv. L. Rev. 261, et seq., by Ames. Ames, Legal Essays, 03, 94.

37 See infra, Sec.Sec. 448, et seq.

38 See, e. g., infra, Sec. 218, an enumeration of statutes making written agreements carry with them a presumption that they were based on sufficient consideration.

39 "All contracts are by the laws of England distinguished into agreements by specialty, and agreements by parol; nor is there any such third class, as some of the counsel have endeavored to maintain, as contracts in writing. If they be merely written and not specialties, they are parol and ft consideration must be proved." Skynthe enforcement of simple contracts, and was the exclusive remedy where the transaction could not be classified as a real contract. The development of the action of assumpsit can best be considered in connection with the law of consideration.40