A rapid development of the Contract Law began in the twelfth century. Several causes contributed to this result. The increased wealth and commerce of the country made a more convenient and highly developed system of contract law an absolute necessity. The surrender, by the Constitution of Clarendon, by the ecclesiastical courts, of their claims to jurisdiction over this subject threw the work upon the common law courts. The Statute of Westminster II, by furnishing the action of assumpsit, gave a convenient method by which contracts other than the real and formal ones could be enforced. The development of the contract law of England is closely connected with the growth of this action and will be discussed under Subject 34, "Common Law Pleading." Additional treatment of contract law will also be found under Subejct 6, "Contracts."