The earliest systematic works on Roman law were the "Manual" of Pomponius, and the "Institutes" of Gaius, who flourished in the time of Hadrian and the Antonines. Both of these works were, for a long time, lost, though fragments were preserved in the pandects of Justinian. In 1816, however, Niebuhr discovered a palimpsest MS., in which the epistles of St. Jerome were written over the erased "Institutes" of Gaius. From the numerous misunderstandings of the Roman historians respecting the laws and constitutional history of their country, the subject continued long in a state of confusion, until Vico, in his "Scienza nuova," dispelled the clouds of error, and reduced it to a system; and he was followed so successfully by Niebuhr, that modern students can have a more comprehensive and antiquarian knowledge of the subject than the writers of the Augustan age. The earliest Roman laws were the "Leges Regiae," which were collected and codified by Sextus Papirius, and were hence called the Papirian code; but these were rude and unconnected--simply a collection of isolated enactments. The laws of the "Twelve Tables" stand next in point of antiquity. They exhibited the first attempt at regular system, and embodied not only legislative enactments, but legal principles. So popular were they that when Cicero was a child every Roman boy committed them to memory, as our children do their catechism, and the great orator laments that in the course of his lifetime this practice had become obsolete. The oral traditional expositions of these laws formed the groundwork of the Roman civil law. To these were added, from time to time, the decrees of the people, the acts of the senate, and praetorian edicts, and from these various elements the whole body of Roman law was composed. So early was the subject diligently studied, that the age preceding the first two centuries of our era was rich in jurists whose powers are celebrated in history. The most eminent jurists who adorned this period were the Scaevolae, a family in whom the profession seems to have been hereditary. After them flourished Aelius Gallus (123-67 B.C.), eminent as a law reformer, C. Juventius, Sextus Papirius, and L. Lucilius Balbus, three distinguished jurists, who were a few years senior to Cicero.