Emperor Justinian I, determined to unify and purify the body of Roman law accumulated over centuries, commissions in 528 the jurist Tribonian to lead a commission of ten legal experts and thirty-nine scribes. The result is the Corpus Juris Civilis ('Body of Civil Law'), compiled in four parts over five years: the Codex (529), which compiles and purifies imperial constitutions from the time of Hadrian onward; the Digest or Pandects (533), a fifty-book encyclopedia summarizing the writings of classical Roman jurists; the Institutes (533), an introductory manual for law students; and the Novels, promulgated after 534 until Justinian's death in 565. The Corpus was drafted almost entirely in Latin — even though most of the empire's population spoke Greek — and gained the force of law throughout the territory. It remained in force in the Byzantine Empire for centuries and was rediscovered in 11th-century Western Europe by the jurists of the University of Bologna, becoming the basis of civil law for most continental-tradition countries to this day.