GAIUS, a celebrated Roman jurist. Of his personal history very little is known. It is impossible to discover even his full name, Gaius or Caius being merely the personal name (prae nomen) so common in Rome. His works were composed between the years 130 and 180, at the time when the Roman empire was most prosperous, and its government the best. Most probably Gaius lived in some provincial town, and hence we find no con temporary notices of his life or works. After his death, however, his writings were recognized as authoritative, and the emperor Valentinian named him, along with Papinian, Ulpian, Modestinus and Paulus, as one of the five jurists whose opinions were to be followed by judicial officers in deciding cases. The works of these jurists accordingly became most important sources of Roman law.
Besides the Institutes, which are a complete exposition of the elements of Roman law, Gaius was the author of a treatise on the Edicts of the Magistrates, of Commentaries on the Twelve Tables, and on the important Lex Papia Poppaea, and several other works. His interest in the antiquities of Roman law makes his work valu able to the historian of early institutions. In the disputes be tween the two schools of Roman jurists he generally attached himself to that of the Sabinians, who were said to be followers of Ateius Capito, of whose life we have some account in the Annals of Tacitus, and to advocate a strict adherence as far as possible to ancient rules, and to resist innovation. Many quota tions from the works of Gaius occur in the Digest of Justinian, and so acquired a permanent place in the system of Roman law ; while a comparison of the Institutes of Justinian with those of Gaius shows that the whole method and arrangement of the later work were copied from that of the earlier, and very numerous passages are word for word the same.
Unfortunately the work was lost to modern scholars, until, in 1816, a manuscript was discovered by B. G. Niebuhr in the chapter library of Verona, in which certain of the works of St. Jerome were written over some earlier writings, which proved to be the lost work of Gaius. The greater part of the palimpsest has, however, been deciphered and the text is now fairly complete. This discovery elucidated portions of the history of Roman law which had previously been obscure.
The Institutes of Gaius are divided into four books—the first treating of persons and the differences of the status they may occupy in the eye of the law; the second of things, and the modes in which rights over them may be acquired, including the law relating to wills ; the third of intestate succession and of obligations ; the fourth of actions and their forms.