The imperfect manuscript, a translation of which is now presented to the American public, was discovered in the Library of the Vatican, by Professor Angelo Mai; a person of singular ingenuity in the detection of those Palimpsests whose contents were written upon ancient writings partially erased. A fac simile of part of the MSS. accompanies this work. The Republic of Cicero was greatly cherished by those who lived in and near his times; of which occasional evidences are found in the writings of antiquity. But the tyranny of the emperors bridled the Romans so soon after its appearance, that Horace, Virgil, Seneca, Quintilian, Pliny, and even Tacitus, have not dared to praise it, lest they should bring down vengeance upon themselves. It is remarkable that while despotism was rapidly extinguishing philosophy and letters, and the very existence of these precious monuments of better times was scarcely thought of; the Christian religion was gradually raising up amidst the persecutions of the primitive church, new champions for truth and justice; to whose works we are indebted for many valuable fragments of the best writers of antiquity, and for almost all the passages of Cicero’s Republic which we were acquainted with, until the late discovery of professor Mai. It is in the works of St. Augustin and of Lactantius that these passages most abound; and they are appealed to by them as most eloquent arguments, in support of just government, and virtuous conduct. Scipio’s Dream, forming the only part of the sixth book which has been preserved, and which is one of the most splendid passages that has been saved from antiquity, has long had a place in the works of Macrobius, a writer at the beginning of the fifth century, addicted to the Pythagorean mysticisms; and who has preserved it probably on account of the occult astronomical relation of numbers contained in it. Notwithstanding the mutilated state of the MSS., the order of the books is distinctly preserved, the general plan of the work is obvious, and we have much greater reason to rejoice at what we possess, than to regret what is wanting. The disordered state of the government and the republic at large, evidently suggested to Cicero this patriotic and bold attempt to stem the influence of bad men, and raise the falling liberties of his country. In this highly philosophical discourse he sought to recall the Romans from the interests of ambitious individuals, and fix their attention upon the greater interests of the country, where each man had a stake: to revive their veneration for the simplicity of the early institutions of Rome, and for the men who had made themselves illustrious by their virtues: and to guard the people more effectually against the innovations and factions now succeeding each other with so much rapidity, he invests those ancient times with a perfection, that the attractions of his eloquence alone can excuse.