When Justinian became sole ruler of the Byzantine Empire in A.D. 527, he ordered the preparation of three compilations of Roman law that together formed the Corpus Juris Civilis. These works have become known individually as the Code, which collected the legal pronouncements of the Roman emperors, the Institutes, an elementary student's textbook, and the Digest, by far the largest and most highly prized of the three compilations. The Digest was assembled by a team of sixteen academic lawyers commissioned by Justinian in 533 to cull everything of value from earlier Roman law. It was for centuries the focal point of legal education in the West and remains today an unprecedented collection of the commentaries of Roman jurists on the civil law.