The requirements for the formation of a simple contract are: (1) Parties of legal capacity; (2) an expression of mutual assent of the parties to a promise, or set of promises, (3) an agreed valid consideration. The agreement must also not be declared void by statute or common law. The requirement last enumerated has often been too broadly stated; namely, that the agreement must not be illegal. But all illegal contracts are not void.1 Possibility of performance, which is also stated by some writers as requisite 2 does not seem essential. Parties may contract to do something which is impossible, if they wish to do so,3 though, doubtless if they know of the impossibility, it will generally be assumed that they do not. Two other supposed requirements have also been suggested: Genuineness of consent, and intent to contract. These do not seem to be properly classed as essential, for the reasons stated in the following sections.

1 See infra, Sec. 1630

2See, e. g., Holland, Jurisprudence (9th ed.), 262.