Justinian authorized Tribonian, then quaestor, "_vir magnificus magisteria dignitate inter agentes decoratus_," for great titles were now given to the officers of the crown, to prepare, with the assistance of seventeen associates, a collection of extracts from the writings of the most eminent jurists, so as to form a body of law for the government of the empire, with power to select and omit and alter; and this immense work was done in three years, and published under the title of Digest or Pandects. "All the judicial learning of former times," says Lord Mackenzie, "was laid under contribution by Tribonian and his colleagues. Selections from the works of thirty-nine of the ablest lawyers, scattered over two thousand separate treatises, were collected in one volume; and care was taken to inform posterity that three millions of lines were abridged and reduced, in these extracts, to the modest number of one hundred and fifty thousand. Among the selected jurists, only three names belonged to the age of the republic; the civilians who flourished under the first emperors are seldom appealed to; so that most of the writers, whose works have contributed to the Pandects, lived within a period of one hundred years. More than a third of the whole Pandects is from Ulpian, and next to him, the principal writers are Paulus, Papinian, Salvius Julianus, Pomponius, Q. Cervidius Scaevola, and Gaius. Though the variety of subjects is immense, the Digest has no claims to scientific arrangement. It is a vast cyclopedia of heterogeneous law badly arranged; every thing is there, but every thing is not in its proper place." [Footnote: Mackenzie, p. 25.] [Sidenote: The Institutes.] But neither the Digest nor the Code was adapted to elementary instruction. It was necessary to prepare a treatise on the principles of Roman law. This was entrusted to Tribonian, and two professors, Theophilus and Dorotheus. It is probable that Tribonian merely superintended the work, which was founded chiefly on the Institutes of Gains, and was divided into four books, and has been universally admired for its method and elegant precision. It was intended merely as an introduction to the Pandects and the Code. [Sidenote: The Novels of Justinian.] The _Novels of Justinian_ were subsequently published, being the new ordinances of the emperor, and the changes he thought proper to make, and are therefore a high authority.