Justinian thereupon 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 sixteen 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. Says Lord Mackenzie: "All the judicial learning of former times 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; everything is there, but everything is not in its proper place." Neither the Digest nor the Code was adapted to elementary instruction; it was therefore necessary to prepare a treatise on the principles of Roman law. This was intrusted 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 Gaius, divided into four books. It has been universally admired for its method and elegant precision. It was intended merely as an introduction to the Pandects and the Code, and was entitled the Institutes. The _Novels_, or _New Constitutions, of Justinian_ were subsequently published, being the new ordinances of the Emperor and the changes he thought proper to make, and were therefore of high authority. The Code, Pandects, Institutes, and Novels of Justinian comprise the Roman law as received in Europe, in the form given by the school of Bologna, and is called the "Corpus Juris Civilis." Savigny says:--