Princeps senatus in the context of "Imperium"

Primus inter pares is a Latin phrase meaning first among equals. It is typically used as an honorary title for someone who is formally equal to other members of their group but is accorded unofficial respect, traditionally owing to their seniority in office.

Historically, the princeps senatus of the Roman Senate was such a figure and initially bore only the distinction that he was allowed to speak first during debate. After the fall of the Republic, Roman emperors initially referred to themselves only as princeps despite having enormous power.

A collegium (pl.: collegia) or college was any association in ancient Rome that acted as a legal entity. Such associations could be civil or religious.The word collegium literally means "society", from collega ("colleague"). They functioned as social clubs or religious collectives whose members worked towards their shared interests. These shared interests encompassed a wide range of the various aspects of urban life; including political interests, cult practices, professions, trade, and civic services. The social connections fostered by collegia contributed to their influence on politics and the economy; acting as lobbying groups and representative groups for traders and merchants.

Some collegia were linked to participating in political violence and social unrest, which resulted in the suppression of social associations by the Roman government. Following the passage of the lex Julia during the reign of Julius Caesar as consul and dictator of the Roman Republic (49–44 BC), and their reaffirmation during the reign of Caesar Augustus as princeps senatus and imperator of the Roman Army (27 BC – 14 AD), collegia required the approval of the Roman Senate or the Emperor in order to be authorized as legal bodies.

The Roman emperors were the rulers of the Roman Empire from the granting of the name and title Augustus to Octavian by the Roman Senate in 27 BC onward. Augustus maintained a facade of Republican rule, rejecting monarchical titles but calling himself princeps senatus (first man of the Senate) and princeps civitatis (first citizen of the state). The title of Augustus was conferred on his successors to the imperial position, and emperors gradually grew more monarchical and authoritarian.

The style of government instituted by Augustus is called the Principate and continued until the late third or early fourth century. The modern word "emperor" derives from the title imperator, that was granted by an army to a successful general; during the initial phase of the empire, the title was generally used only by the princeps. For example, Augustus's official name was Imperator Caesar Divi Filius Augustus. The territory under command of the emperor had developed under the period of the Roman Republic as it invaded and occupied much of Europe and portions of North Africa and the Middle East. Under the republic, the Senate and People of Rome authorized provincial governors, who answered only to them, to rule regions of the empire. The chief magistrates of the republic were two consuls elected each year; consuls continued to be elected in the imperial period, but their authority was subservient to that of the emperor, who also controlled and determined their election. Often, the emperors themselves, or close family, were selected as consul.

Marcus Aemilius Lepidus (c. 230 – 152 BC) was a Roman consul, Pontifex Maximus, Censor and Princeps Senatus. A scion of the ancient Patrician gens Aemilia, he was most likely the son of Marcus Aemilius Lepidus, with his brothers being Lucius and Quintus.

According to Polybius, Lepidus was "the handsomest man of his time," as well as, in the words of Diodorus, being "gifted with superior intelligence". Combining these qualities with an impeccable aristocratic birth, political skill and a reputation for bravery, Lepidus soon rose to become one of the leading Romans of his generation.

Marcus Aemilius Scaurus (c. 159 – c. 89 BC) was a Roman statesman who served as consul in 115 BC. He was also a long-standing princeps senatus, occupying the post from 115 until his death in late 89 or early 88 BC, and as such was widely considered one of the most prestigious and influential politicians of the late Republic.

After his consulship, Scaurus wrote De vita sua, which was probably the first autobiography in Roman history.

De vita sua ("On my life") is an autobiography written by Marcus Aemilius Scaurus (c. 161–c. 89 BC), a prominent statesman of the Roman Republic, notably consul in 115 BC and princeps senatus for a generation. Even though the book is lost and has only survived in seven small fragments, it is the first known autobiography in Roman history. Scaurus wrote his autobiography in order to defend his actions throughout his long career, during which he was at the centre of Roman politics, from the tribunates of Gaius Gracchus to the Social War, and engaged in bitter feuds with numerous enemies. Most scholars think that Scaurus wrote the autobiography towards the end of his life.

Although Scaurus' book was not particularly successful and already forgotten by the time of Cicero—a great admirer of Scaurus and his work, it marked the beginning of a long tradition of Roman politicians writing their memoirs or autobiographical accounts, such as Rutilius Rufus, Sulla, Caesar, Augustus, and later Roman emperors down to Septimius Severus.