 sale, lease, partnership and mandate) was mutual assent ("consensus ad idem") ‘clothed’ in solemnities sufficient to make the agreement enforceable.Any agreement that did not rigidly conform to the four types was referred to as a "nudum pactum" and was not actionable unless there had been part performance.The development of contracts "consensu" was prompted by the commercial needs of the growing Roman state, but Roman law never reached the point of enforcing all serious and deliberate agreements as contracts.