Justinian's Institutes was one part of his effort to codify Roman law and to reform legal education, of which the Digest also was a part.[2] Whereas the Digest was to be used by advanced law students, Justinian's Institutes was to be a textbook for new students.[3] The need for a new text for first year students was addressed as early as 530 in the constitution "Deo auctore," where reference is made to something "...which may be promulgated to replace the elementary works, so that the raw intelligence of the student, nourished by a simple diet, may proceed more easily to advanced legal studies."[4] Under the supervision of Tribonian, two law professors (Theophilus and Dorotheus) were assigned to extract statements about the basic institutions ("Institutiones") of Roman law from the teaching books created by writers of "authority" (as defined in the Law of Citations). The bulk of this new Institutes is the Institutes of Gaius, much of it taken verbatim; but it also uses material from the Institutes of Marcian, Florentinus, Ulpian, and perhaps Paulus (the other writers of "authority."[5] There is some debate over which of the commission members is responsible for what part of the new Institutes. Most recently it has been suggested that Theophilus and Dorotheus created the extracts taken from the older works, while Tribonian revised and added new imperial laws.[6]