A gifted poet and outstanding Islamic Scholar, Abu Abdullah Muhammad ibn Idris al-Shafi'i (767-820) firmly rejected the use of common sense alone in Islamic legal rulings, arguing that the only valid sunnah (or prophetic religious traditions) were those directly handed down from Muhammad by Hadith. In this innovative study, Kecia Ali examines the life and thought of the forefather of the second largest of the four principal Sunni schools of jurisprudence, the Sh?fi'i.