De re publica (On the Commonwealth; see below) is a dialogue on Roman politics by Cicero, written in six books between 54 and 51 BC. The work does not survive in a complete state, and large parts are missing. The surviving sections derive from excerpts preserved in later works and from an incomplete palimpsest uncovered in 1819. Cicero uses the work to explain Roman constitutional theory. Written in imitation of Plato’s "Republic", it takes the form of a Socratic dialogue in which Scipio Aemilianus takes the role of a wise old man.