by the religious and ethical precepts of Islam. It continued some aspects of pre-Islamic laws and customs of the lands that fell under Muslim rule in the aftermath of the early conquests and modified other aspects, aiming to meet the practical need of establishing Islamic norms of behavior and adjudicating disputes arising in the early Muslim communities. Juristic thought gradually developed in study circles, where independent scholars met to learn from a local master and discuss religious topics. At first, these circles were fluid in their membership, but with time distinct regional legal schools crystallized around shared sets of methodological principles. As the boundaries of the schools became clearly delineated, the authority of their doctrinal tenets came to be vested in a master jurist from earlier times, who was henceforth identified as the school's founder. In the course of the first three centuries of Islam, all legal schools came to accept the broad outlines of classical legal theory, according to which Islamic law had to be firmly rooted in the Quran and hadith. Traditional jurisprudence (fiqh) Fiqh is traditionally divided into the fields of uṣūl al-fiqh (lit. the roots of fiqh), which studies the theoretical principles of jurisprudence, and furūʿ al-fiqh (lit. the branches of fiqh), which is devoted to elaboration of rulings on the basis of these principles. Principles of jurisprudence (uṣūl al-fiqh) Classical jurists held that human reason is a gift from God which should be exercised to its fullest capacity. However, they believed that use of reason alone is insufficient to distinguish right from wrong, and that rational argumentation must draw its content from the body of transcendental knowledge revealed in the Quran and through the sunnah of Muhammad. Traditional theory of Islamic jurisprudence elaborates how scriptures should be interpreted from the standpoint of linguistics and rhetoric. It also comprises methods for establishing authenticity of hadith and for determining when the legal force of a scriptural passage is abrogated by a passage revealed at a later date. In addition to the Quran and sunnah, the classical theory of Sunni fiqh recognizes two other sources of law: juristic consensus (ijmaʿ) and analogical reasoning (qiyas). It therefore studies the application and limits of analogy, as well as the value and limits of consensus, along with other methodological principles, some of which are accepted by only certain legal schools. This interpretive apparatus is brought together under the rubric of ijtihad,