Prior to the rise of classical economics in the eighteenth century, the economies in Europe and its North American colonies were governed by a variety of (formal and informal) regulations designed to prevent "greed" from overcoming "morality". In its most formal manifestations, examples such as the traditional Christian and Muslim prohibitions on usury represent the limits imposed by religious values on economic activity, and as such are part of the moral economy. Laws that determine what sort of contracts will be given effect by the judiciary, and what sort of contracts are void or voidable, often incorporate concepts of a moral economy; in many jurisdictions, traditionally a contract involving gambling was considered void in law because it was against public policy. These restrictions on freedom of contract are the results of moral economy. According to the beliefs which inspired these laws, economic transactions were supposed to be based on mutual obligation, not individual gain. In colonial Massachusetts, for example, prices and markets were highly regulated, even the fees physicians could charge.