Our evidence for the text of the Republic is threefold. (1) The incomplete Vatican manuscript, shelfmarked Vat. lat. 5757, was brought to light in 1820 by Cardinal Angelo Mai, Prefect of the Vatican Library. It is an eighth-century copy of St Augustine's commentary on the Psalms, written at the monastery of Bobbio in northern Italy. Mai detected the traces of an earlier text, which proved to be that of the Republic. It was common practice in the early Middle Ages to reuse the parchment from old books, after first making an attempt to wash off the original script. Such recycled manuscripts are called 'palimpsests'. Using chemical reagents to enhance the clarity of the older script, Mai recovered about a quarter of the original text, which was evidently a luxury edition of the Republic written in uncial script in the fourth or fifth century. The pages were out of order, but the original order could be reconstructed partly from context and partly from the signature numbers which the original scribes had marked at the foot of some of the pages. Subsequent editors have made only minor adjustments. (A photograph of a page of the manuscript may conveniently be found in Reynolds and Wilson, plate 10.) The text in this manuscript contains many errors, but the correct reading is in many cases inserted by an early annotator who appears to have had access to an equally or more reliable text. (2) A number of fragments of the text are preserved as quotations in later writers, particularly Lactantius, Augustine, and the grammarian Nonius Marcellus. The fragments have been fully re-examined by Heck. We have omitted some of the shorter fragments and those whose placing or authenticity is doubtful. (3) The 'Dream of Scipio' survives, often in association with the commentary of Macrobius, in an independent manuscript tradition of which the earliest representative ( Paris, nouv. acq. lat. 454) dates from the ninth century.
The Laws survives as part of what is called the Leiden corpus, a collection of Cicero's philosophical works preserved principally in three medieval manuscripts held at the Bibliotheek der Rijksuniversiteit, Leiden. The text as we have it breaks off at or before