The Romans summed up their political existence in a single phrase: senatus populusque Romanus, “the Senate and the Roman people,” which they abbreviated “SPQR.” This sentiment reflects the republican ideal of shared government rather than power concentrated in a monarchy. It stands for the beliefs, customs, and laws of the republic — the unwritten constitution that evolved over two centuries to meet the demands of the governed. SPQR became a shorthand way of saying “Rome,” just as U.S.A. says “the United States of America.”

In the early republic social divisions determined the shape of politics. Political power was in the hands of a hereditary aristocracy — the patricians, whose privileged legal status was determined by their birth as members of certain families. Patrician men dominated the affairs of state, provided military leadership in time of war, and monopolized knowledge of law and legal procedure. The common people of Rome, the plebeians (plih-BEE-uhns), were free citizens with a voice in politics, but they had few of the patricians’ political and social advantages. While some plebeian merchants increased their wealth in the course of Roman expansion and came to rival the patricians economically, most plebeians were poor artisans, small farmers, and landless urban dwellers.

The Romans created several assemblies through which men elected high officials and passed legislation. The earliest was the Centuriate Assembly, in which citizens were organized into groups called centuries based loosely around their status in the military. Each citizen was assigned to a century depending on his status and amount of wealth, and the patricians possessed the majority of centuries. When an election was ordered, each century met separately and voted as a bloc, which meant that the patricians could easily outvote the plebeians. In 471 B.C.E. plebeian men won the right to meet in an assembly of their own, the concilium plebis, and to pass ordinances.

The highest officials of the republic were the two consuls, who were elected for one-year terms by the Centuriate Assembly. At a later time Romans believed that the consulship had initially been open only to patrician men, although surviving lists of consuls actually show that a few early consuls were plebeians. The consuls commanded the army in battle, administered state business, presided over the Senate and assemblies, and supervised financial affairs. In effect, they ran the state. The consuls appointed quaestors (KWEH-stuhrs) to assist them in their duties, and in 421 B.C.E. the quaestorship became an elective office open to plebeian men. The quaestors took charge of the public treasury and investigated crimes, reporting their findings to the consuls.

In 366 B.C.E. the Romans created a new office, that of praetor (PREE-tuhr). When the consuls were away from Rome, the praetors could act in their place; they could also command armies, be governors in the provinces, interpret law, and administer justice. Other officials included the powerful censors who had many responsibilities, the most important being supervision of public morals, the power to determine who lawfully could hold public office and sit in the Senate, the registration of citizens, the taking of a census, and the leasing of public contracts.

The most important institution of the republic was the Senate, a political assembly that by tradition was established by Romulus and in reality most likely originated in the monarchical period as a council of the heads of powerful families who advised the king. By the time written records begin for Roman history, the Senate was already in existence. During the republic the Senate grew to several hundred members, all of whom had previously been elected to one of the high positions, which automatically conferred Senate membership. Because the Senate sat year after year with the same members, while high officials changed annually, it provided stability and continuity. It passed formal decrees that were technically “advice” to the magistrates, who were not bound to obey them but usually did. It directed the magistrates on the conduct of war and had the power over the expenditure of public money. In times of emergency it could name a dictator. Technically the Senate could not pass binding legislation during the republican period. Its decisions had to be put to the Centuriate Assembly for a vote before they could become law, but patricians dominated both groups and generally agreed on legislative matters.

Within the city of Rome itself the Senate’s powers were limited by laws and traditions, but as Rome expanded, the Senate had greater authority in the outlying territories. The Romans divided the lands that they conquered into provinces, and the Senate named the governors for these, most of whom were former consuls or praetors. Another responsibility of the Senate was to handle relations between Rome and other powers.

A lasting achievement of the Romans was their development of law. Roman civil law, the ius civile, consisted of statutes, customs, and forms of procedure that regulated the lives of citizens. As the Romans came into more frequent contact with foreigners, the consuls and praetors applied a broader ius gentium, the “law of the peoples,” to such matters as peace treaties, the treatment of prisoners of war, and the exchange of diplomats. In the ius gentium all sides were to be treated the same regardless of their nationality. By the late republic Roman jurists had widened this principle still further into the concept of ius naturale, “natural law,” based in part on Stoic beliefs (see “Philosophy and the People” in Chapter 4). Natural law, according to these thinkers, is made up of rules that govern human behavior that come from applying reason rather than customs or traditions, and so apply to all societies. In reality, Roman officials generally interpreted the law to the advantage of Rome, of course, at least to the extent that the strength of Roman armies allowed them to enforce it. But Roman law came to be seen as one of the most important contributions Rome made to the development of Western civilization.