sharia, the religious law of Islam. As Islam makes no distinction between religion and life, Islamic law covers not only ritual but many aspects of life. The actual codification of canonic law is the result of the concurrent evolution of jurisprudence proper and the so-called science of the roots of jurisprudence (usul al-fiqh). A general agreement was reached, in the course of the formalization of Islam, as to the authority of four such roots: the Qur'an in its legislative segments; the example of the Prophet Muhammad as related in the hadith; the consensus of the Muslims (ijma), premised on a saying by Muhammad stipulating "My nation cannot agree on an error"; and reasoning by analogy (qiyas). Another important principle is ijtihad, the extension of sharia to situations neither covered by precedent nor explicable by analogy to other laws. These roots provide the means for the establishment of prescriptive codes of action and for the evaluation of individual and social behavior. The basic scheme for all actions is a fivefold division into obligatory, meritorious, permissible, reprehensible, and forbidden.